TransAM™

p53 Transcription Factor
Assay Kits
(version D1)
Catalog Nos. 41196 & 41696

Revision

Date

Description of Change

D1

January, 2024

The p53 antibody has been replaced by a new
rabbit monoclonal antibody which will react with
p53 of human and African green monkey origin.
The new antibody will perform similarly to theprevious one in the assay. There is no change tothe protocol. Please refer to the TDS with the lot#of antibody received in the kit for
performance data.

TABLE OF CONTENTS

Page

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Flow Chart of Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Introduction
p53 Transcription Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Transcription Factor Assays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
TransAM p53 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Kit Performance and Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Kit Components and Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Protocols
Buffer Preparation and Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Quick Chart for Preparing Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
p53 Transcription Factor Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Preparation of Nuclear Extract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Appendix
Section A. Troubleshooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Technical Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

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Overview
The tumor suppressor p53 acts primarily as a transcriptional activator that controls the expression of many genes implicated in cell growth control, DNA repair, apoptosis, redox regulation,
nitric oxide production and protein degradation. Mutational inactivation of the p53 gene productis one of the most common genetic events that occur in human cancers. Therefore, accuratemonitoring of p53 activation in cells, tissues or animals is crucial for biomedical research anddrug development. To date, such research projects are tedious and time consuming, and lackhigh-throughput screening methods.
With its patented TransAM™ method*, Active Motif introduced the first ELISA-based kits to detectand quantify transcription factor activation. TransAM Kits combine a fast, user-friendly format
with a sensitive, specific assay. TransAM p53 Kits are designed specifically for the study of the
p53 activation pathway. They contain a 96-well plate to which an oligonucleotide containing
the p53 consensus binding site has been immobilized. p53 contained in nuclear extracts binds
specifically to this oligonucleotide and is detected through use of an antibody directed against
p53. Addition of a secondary antibody conjugated to horseradish peroxidase (HRP) provides asensitive colorimetric readout that is easily quantified by spectrophotometry. The 96-well platewith individual strips of 8 wells is suitable for manual use or for high-throughput screening applications. TransAM p53 Kits are available in two sizes:
product
TransAM p53

formatcatalog no.

1 x 96-well plate5 x 96 well plates

41196
41696

* Technology covered by AAT-filed patents and licensed to Active Motif.

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1Flow Chart of Process

2

1

5

4

3

7

6

8

9

10

11

12

A
B
C
D
E

Cell extractcontaining activatedtranscription factor

F
G
H

Oligonucleotide
coated plate

Add cell
extract
21

11

01

9

8

7

6

5

4

3

2

1
A
B

C
D
E
F
G
H

Add primary
antibody

1 hr.
3

2

1

9

8

7

6

5

4

10

11

12

A
B
C
D
E
F
G
H

Add anti-IgG
HRP conjugate
21

11

01

9

8

7

6

5

4

1 hr.
3

2

1
A
B

C
D
E
F
G

Add developing
and stop solution

H

1 hr.
2

1

5

4

3

7

6

A
B
C
D
E
F
G
H

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2

8

9

10

11

12

Introduction
p53 Transcription Factor
The tumor suppressor protein p53 is a transcription factor that switches on a series of protective
genes when the cell is exposed to stressful events. Many solid tumors contain defective formsof p53 that are unable to stop cells from proliferating when, for example, their DNA has beendamaged. Therefore, p53 functions to selectively destroy stressed or abnormal cells, thereby
protecting the organism from cancer development1. Stress events include radiation, low pH, heatshock, hypoxia, genotoxins, DNA damage, RNA polymerase II block and oxidant injury2. Twohuman p53 homologues, p73 and p63 were recently identified with roles in stem cell identity,
neurogenesis, natural immunity and homeostatic control3-5. These homologues can drive gene
expression from promoters similar to that bound by p53, but neither of these have been foundto be highly mutated in cancers, nor is p73 bound to viral oncoproteins that neutralize p53 protein activity, so their function in regulating p53-dependent cancer progression is unclear.
p53 possesses a modular architecture with an N-terminal transactivation domain, a strongly conserved core DNA-binding domain, a tetramerization domain, and a regulatory C terminus. The
p53 DNA-binding domain comprises several hot spot regions for mutation that inactivate p53
in more than half of all human tumors6. Tetrameric p53 binds specifically to a DNA consensus
sequence consisting of two consecutive palindromic 10-bp half-sites 5´-RRRCWWGYYY-3´(R = A or G, Y = C or T, W = A or T), which can be separated from 0 to 13 bp7. The tetramer
assembly stabilizes the p53 monomer folding and increases the DNA-binding activity of p53.
p53 stays inactive in the nucleus when bound to MDM2 protein, an E3 ubiquitin ligase that targets both p53 and itself for ubiquitination. MDM2 represses p53 activity by inducing its nuclear
export and degradation in proteasomes8, 9. Stress signals, such as DNA damage, activate protein kinases that lead to p53 phosphorylation of numerous sites and subsequent activation of
p53 by inhibiting p53-MDM2 interaction10. MDM2 gene expression is regulated by p53, creating
a feedback loop in which p53 activates expression of MDM2, which keeps p53 levels low during
normal growth and development.

Transcription Factor Assays
To date, three methods are widely used to measure p53 activation, either directly or indirectly:
1.

p53 activation can be determined by Western Blot by using antibodies specific for p53
protein. This method is time consuming (up to 2 days once the nuclear cell extracts areprepared), and is not suitable for processing large numbers of samples.

2.

The DNA-binding capacity of p53 can be assayed by gel retardation, also called electrophoretic mobility shift assay (EMSA). In this method, nuclear extracts are incubatedwith a radioactive double-stranded oligonucleotide probe containing the consensus
sequence for p53 binding. If p53 is active in the nuclear extract, it will bind to the probe.
Samples are then resolved by electrophoresis on a native polyacrylamide gel, followedby autoradiography. This method is sensitive, but like the previous procedure, it is time
consuming (multiple days of gel exposure may be required to achieve sufficient sensitivity)
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3and it cannot be applied to high-throughput screening. Gelshift assays also require special
precautions and equipment for handling radioactivity.
3.

Another method used to assay p53 activation is based on reporter genes, typically luciferase or β-galactosidase, placed under the control of a promoter containing a p53 consensus
binding site. The promoter can be artificial, made of several 10-bp half-sites and a TATA
box, or natural, like promoter sequences from cell cycle check point or pro-apoptotic proteins. However, the procedure is limited by the following issues: (i) reporter gene assays
have to be repeated several times to obtain statistically reliable data; and (ii) reporter geneassays are sensitive to confounding factors that may influence the expression level of thereporter gene, and therefore assays have to be carefully standardized. Reporter geneassays are sensitive and easy to perform with a large number of samples, but require efficient cell transfection with the reporter plasmid.

TransAM p53
p53 is involved in cell proliferation and therefore represents an excellent pharmacological target
to develop drugs for inhibiting angiogenesis and metastasis in cancers. However, pharmaceutical research in this field has been hampered by the lack of convenient assays suitable for highsample number experiments.
To overcome this, Active Motif is introducing a high-throughput assay to quantify p53 activation11. The TransAM Kit combines a fast and user-friendly ELISA format with a sensitiveand specific assay for transcription factors. TransAM p53 Kits contain a 96-well plate on
which has been immobilized an oligonucleotide that contains a p53 consensus binding site
(5´-GGACATGCCCGGGCATGTCC-3´). p53 contained in nuclear extract specifically binds to thisoligonucleotide. The primary antibody used in TransAM p53 Kit recognizes an accessible epitopeon p53 protein upon DNA binding. Addition of a secondary HRP-conjugated antibody provides
a sensitive colorimetric readout easily quantified by spectrophotometry. Once the nuclear
extracts are prepared, this assay is completed in less than 3.5 hours. As this assay is performed
in 96-well plates, a large number of samples can be handled simultaneously, enabling highthroughput automation. This assay is specific for p53 activation and has been shown to be 5-foldmore sensitive and 20-fold faster than the gel-retardation technique. With the 3.5-hour TransAM
procedure, we could detect p53 activation using as little as 0.6 µg of nuclear extract from H2O2treated cells. A comparable assay using EMSA required 5 µg of nuclear extract and a 3-day
autoradiography.
TransAM has many applications including the study of drug potency toward p53 binding, p53transcriptional activity regulation and protein structure/function studies of p53 and its mutatedvariants in areas such as angiogenesis, metastasis, tumorigenesis, and many more.

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4Kit Performance and Benefits
The TransAM p53 Kit is for research use only. Not for use in diagnostic procedures.
Detection limit: < 0.6 µg nuclear extract/well. TransAM p53 is 5-fold more sensitive than EMSA.
Range of detection: TransAM provides quantitative results from 0.6 to 10 µg of nuclear extract/well (see graph below).
Cross-reactivity: TransAM p53 detects p53 from human and African green monkey origin.
Assay time: 3.5 hours. TransAM is 20-fold faster than EMSA.

p53 activation (OD 450nm)

2.5

y = 0.222x+ 0.055 r2 = 0.997

2

1.5

untreated

H2O2-treated

1

0.5

0

0

2.5

5

7.5

10

12.5

Cell extract (g/well)
Monitoring p53 activation with the TransAM p53 Kit: Different amounts of nuclear extracts from untreated(opened squares) and H2O2-treated (filled circles) MCF-7 cells are tested for p53 activation by using theTransAM p53 Kit. These curves are provided for demonstration only.

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5Kit Components and Storage
Except for the nuclear extract that must be kept at -80ºC, kit components can be stored at -20ºCprior to first use. Then, we recommend storing each component at the temperature indicated in
the table below.
Reagents

Quantity
1 plate / 5 plates

Storage / Stability

p53 antibody

11 µl / 55 µl(0.2 mg/ml)-20°C for 6 months

Anti-rabbit HRP-conjugated IgG

11 µl / 55 µl(0.4 mg/ml)

4°C for 6 months

Wild-type oligonucleotide AM21

100 µl / 500 µl(10 pmol/µl)-20°C for 6 months

Mutated oligonucleotide AM21

100 µl / 500 µl(10 pmol/µl)-20°C for 6 months

MCF-7 (H2O2) nuclear extract

40 µl / 200 µl(2.5 mg/ml)-80°C for 6 months

Dithiothreitol (DTT)

100 µl / 500 µl(1 M)-20°C for 6 months

Protease Inhibitor Cocktail

100 µl / 500 µl-20°C for 6 months

Poly [d(I-C)]

100 µl / 500 µl(17 µg/ml)-20°C for 6 months

Lysis Buffer AM2

10 ml / 50 ml

4°C for 6 months

Binding Buffer AM5

10 ml / 50 ml

4°C for 6 months

10X Wash Buffer AM2

22 ml / 110 ml

4°C for 6 months

10X Antibody Binding Buffer AM2

2.2 ml / 11 ml

4°C for 6 months

Developing Solution

11 ml / 55 ml

4°C for 6 months

Stop Solution

11 ml / 55 ml

4°C for 6 months

96-well p53 assay plate

1/5

4°C for 6 months

Plate sealer

1/5

Additional materials required

For Nuclear Extract preparation• Multi-channel pipettor• Hypotonic Buffer• Multi-channel pipettor reservoirs• Phosphatase Inhibitor Buffer• Rocking platform• 10X PBS

• Microplate spectrophotometer capableof reading at 450 nm (655 nm as
optional reference wavelength)• Detergent (NP-40)

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6

Protocols
Buffer Preparation and Recommendations
Preparation of Complete Lysis Buffer
We provide an excess of Lysis Buffer AM2 in order to perform the assay AND to prepare customized cell extracts. Our Nuclear Extract Kit can also be purchased separately (Cat. Nos. 40010 &
40410). Prepare the amount of Complete Lysis Buffer required for the assay by adding 1 µl of 1
M DTT and 10 µl of Protease Inhibitor Cocktail per ml of Lysis Buffer AM2 (see the Quick Chartfor Preparing Buffers in this section). Some of the protease inhibitors lose their activity after 24hours once diluted. Therefore, we recommend using the Complete Lysis Buffer immediately forcell lysis. The remaining amount should be discarded if not used in the same day.
Preparation of Complete Binding Buffer
Prepare the amount of Complete Binding Buffer AM5 required for the assay by adding 1 µl of
DTT and 10 µl of 17 µg/ml poly[d(l-C)] per ml of Binding Buffer (see the Quick Chart for Preparing
Buffers in this section). After use, discard remaining Complete Binding Buffer.
Preparation of 1X Wash Buffer
Prepare the amount of 1X Wash Buffer required for the assay as follows: For every 100 ml of
1X Wash Buffer required, dilute 10 ml 10X Washing Buffer AM2 with 90 ml distilled water (seethe Quick Chart for Preparing Buffers in this section). Mix gently to avoid foaming. The 1X Wash
Buffer may be stored at 4°C for one week. The Tween 20 contained in the 10X Wash Buffer AM2
may form clumps, therefore homogenize the buffer by incubating at 50ºC for 2 minutes and mixing prior to use.
Preparation of 1X Antibody Binding Buffer
Prepare the amount of 1X Antibody Binding Buffer required for the assay as follows: For every
10 ml of 1X Antibody Binding Buffer required, dilute 1 ml 10X Antibody Binding Buffer AM2 with
9 ml distilled water (see the Quick Chart for Preparing Buffers in this section)*. Mix gently to
avoid foaming. Discard remaining 1X Antibody Binding Buffer after use. The BSA contained in the
10X Antibody Binding Buffer AM2 may form clumps, therefore homogenize the buffer by warming to room temperature and vortexing for 1 minute prior to use. Dilute both primary and HRPconjugated secondary antibodies to 1:1000 with the 1X Antibody Binding Buffer. Depending on
the particular assay, the signal:noise ratio may be optimized by using higher dilutions of both
antibodies. This may decrease the sensitivity of the assay.
* Volumes listed refer to the preparation of buffer for diluting both the primary & secondary antibodies.

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7Developing Solution
The Developing Solution should be warmed to room temperature before use. The Developing
Solution is light sensitive, therefore, we recommend avoiding direct exposure to intense lightduring storage. The Developing Solution may develop a yellow hue over time. This does notaffect product performance. A blue color present in the Developing Solution indicates that it
has been contaminated and must be discarded. Prior to use, place the Developing Solution atroom temperature for at least 1 hour. Transfer the amount of Developing Solution required forthe assay into a secondary container before aliquoting into the wells (see the Quick Chart for
Preparing Buffers in this section). After use, discard remaining Developing Solution.
Stop Solution
Prior to use, transfer the amount of Stop Solution required for the assay into a secondary
container (see the Quick Chart for Preparing Buffers in this section). After use, discard remaining
Stop Solution.
WARNING:

The Stop Solution is corrosive. Wear personal protective equipment whenhandling, i.e. safety glasses, gloves and labcoat.

Nuclear extract
The MCF-7 (H2O2) nuclear extract is provided as a positive control for p53 activation. Sufficient
extract is supplied for 25 reactions per plate. This extract is optimized to give a strong signal
when used at 5 µg/well. We recommend aliquoting the extract in 10 µl fractions and storing at-80ºC. Avoid multiple freeze/thaw cycles of the extract. Various cell extracts are available from
Active Motif (see Appendix, Section B. Related Products).
Wild-type and mutated consensus oligonucleotides
The wild-type consensus oligonucleotide is provided as a competitor for p53 binding in orderto monitor the specificity of the assay. Used at 20 pmol/well, the oligonucleotide will prevent
p53 binding to the probe immobilized on the plate. Conversely, the mutated consensus oligonucleotide should have no effect on p53 binding. Prepare the required amount of wild-type and/or mutated consensus oligonucleotide by adding 2 µl of appropriate oligonucleotide to 43 µl ofComplete Binding Buffer per well being used (see the Quick Chart for Preparing Buffers in thissection). To allow for optimum competition, add the oligonucleotide to the well prior to additionof the cell extract.
Optional- Preparation of standard curve
For those who wish to quantify the amount of p53 in their samples, Active Motif offers recombinant p53 for use as a protein standard (see Appendix, Section B. Related Products).
1.

Begin with a 100 ng/µl working stock of recombinant protein (use the TransAM Complete
Lysis Buffer to dilute the protein). Set up a standard curve in duplicate using the following
concentrations: 2.0, 1.0, 0.5, 0.25, 0.125, 0.0625, 0.0312 and 0 ng/µl. Note: The preceding
range is provided as guidance, a broader range of values may be used.

2.

Make up a 2.0 ng/µl solution by adding 2.0 µl of the 100 ng/µl working stock to 98 µl ofComplete Lysis Buffer. Next, pipette 60 µl of Complete Lysis Buffer into the 7 remaining
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8

tubes. Use the 2.0 ng/µl solution to prepare a dilution series as indicated below. Be sure tomix each tube thoroughly before each transfer. The 2.0 ng/µl standard serves as the highstandard, while Complete Lysis Buffer alone serves as the 0.0 ng/µl.
3.

10 µl from each tube will be aliquoted to the wells in Step 1, No. 2 of the protocol and willcorrespond to the following quantities of p53: 20, 10, 5, 2.5, 1.25, 0.625, 0.312 and 0.0 ng/
well.
60 µl

2.0 ng/µl

60 µl

1.0 ng/µl

60 µl

0.5 ng/µl

60 µl0.25 ng/µl

60 µl

60 µl

0.125 ng/µl 0.0625 ng/µl 0.0312 ng/µl

Quick Chart for Preparing Buffers
Reagents to prepare

Components

For 1
well

For 1 strip(8 wells)

For 6 strips(48 wells)

For 12 strips(96 wells)

Complete Lysis Buffer

DTT
Protease inhibitor cocktail
Lysis Buffer AM2
TOTAL REQUIRED

0.01 µl0.12 µl11.12 µl11.25 µl

0.1 µl0.9 µl
89 µl
90 µl

0.6 µl5.4 µl534 µl540 µl1.2 µl10.8 µl
1.068 ml
1.08 ml

Complete Binding Buffer

DTT
Poly [d(l-C)]
Binding Buffer AM5
TOTAL REQUIRED

0.05 µl0.45 µl44.5 µl
45 µl

0.4 µl
3.6 µl356 µl360 µl

2.4 µl21.6 µl2.136 ml
2.16 ml

4.8 µl43.2 µl
4.272 ml
4.32 ml

Complete Binding Buffer
with wild-type ormutated oligonucleotide

Wild-type or mutated oligo
Complete Binding Buffer
TOTAL REQUIRED

2 µl
43 µl
45 µl

16 µl
344 µl360 µl

96 µl
2.064 ml
2.16 ml

N/A
N/A
N/A

1X Wash Buffer

Distilled water
10X Wash Buffer AM2
TOTAL REQUIRED

2.025 ml
225 µl2.25 ml

16.2 ml
1.8 ml18 ml

97.2 ml
10.8 ml
108 ml194.4 ml21.6 ml
216 ml1X Antibody
Binding Buffer*

Distilled water
10X Ab Binding Buffer AM2
TOTAL REQUIRED

202.5 µl22.5 µl
225 µl1.62 ml
180 µl
1.8 ml9.72 ml
1.08 ml
10.8 ml19.44 ml
2.16 ml21.6 ml

Developing Solution

TOTAL REQUIRED

112.5 µl

900 µl5.4 ml10.8 ml

Stop Solution

TOTAL REQUIRED

112.5 µl

900 µl5.4 ml10.8 ml* Volumes listed refer to the preparation of buffer for diluting both the primary & secondary antibodies.

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9p53 Transcription Factor Assay
Determine the appropriate number of microwell strips required for testing samples, controls andblanks in duplicate. If less than 8 wells in a strip need to be used, cover the unused wells witha portion of the plate sealer while you perform the assay. The content of these wells is stable atroom temperature if kept dry and, therefore, can be used later for a separate assay. Store theunused strips in the aluminum pouch at 4°C. Use the strip holder for the assay.
Prepare the Complete Lysis Buffer, Complete Binding Buffer, 1X Wash Buffer and 1X Antibody
Binding Buffer as described above in the section Buffer Preparation and Recommendations. Multichannel pipettor reservoirs may be used for dispensing the Complete Binding Buffer, Wash Buffer,
Antibody Binding Buffer, Developing Solution and Stop Solution into the wells being used.
Step 1: Binding of p53 to its consensus sequence1.

Add 40 µl Complete Binding Buffer to each well to be used. If you wish to perform competitive binding experiments, add 40 µl Complete Binding Buffer containing 20 pmol (2 µl) of
the wild-type or mutated consensus oligonucleotide (see the Buffer Preparation section
above for a description of comptitive binding).

2.

Sample wells: Add 10 µl of sample diluted in Complete Lysis Buffer per well. We recommend using 2-10 µg of nuclear extract diluted in Complete Lysis Buffer per well. A protocol
for preparing nuclear extracts can be found on pgae 12.
Positive control wells: Add 5 µg of the provided MCF-7 nuclear extract diluted in 10 µl ofComplete Lysis Buffer per well (2 µl of extract in 8 µl of Complete Lysis Buffer per well).
Blank wells: Add 10 µl Complete Lysis Buffer only per well.
OPTIONAL – Protein standard wells: Add 10 µl of the appropriate protein standard dilutedin Complete Lysis Buffer to each well being used (see page 8, Preparation of standard
curve).

3.

Use the provided adhesive cover to seal the plate. Incubate for 1 hour at room temperature
with mild agitation (100 rpm on a rocking platform).

4.

Wash each well 3 times with 200 µl 1X Wash Buffer. For each wash, flick the plate over asink to empty the wells, then tap the inverted plate 3 times on absorbent paper towels.

Step 2: Binding of primary antibody1.

Add 100 µl diluted p53 antibody (1:1000 dilution in 1X Antibody Binding Buffer) to all wells being used.

2.

Cover the plate and incubate for 1 hour at room temperature without agitation.

3.

Wash the wells 3 times with 200 µl 1X Wash Buffer (as described in Step 1, No. 4).

Step 3: Binding of secondary antibody1.

Add 100 µl of diluted HRP antibody (1:1000 dilution in 1X Antibody Binding Buffer) to all wells being
used.

2.

Cover the plate and incubate for 1 hour at room temperature without agitation.

3.

During this incubation, place the Developing Solution at room temperature.
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10

4.

Wash the wells 4 times with 200 µl 1X Wash Buffer (as described in Step 1, No. 4).

Step 4: Colorimetric reaction
1.

Transfer the amount of Developing Solution required for the assay into a secondary container. Add 100 µl Developing Solution to all wells being used.

2.

Incubate 5-10 minutes at room temperature protected from direct light. Please read theCertificate of Analysis supplied with this kit for the optimal development time for this specific kit lot, which varies from lot to lot. Monitor the blue color development in the sample
and positive control wells until it turns medium to dark blue. Do not overdevelop.

3.

Add 100 µl Stop Solution. In presence of the acid, the blue color turns yellow.

4.

Read absorbance on a spectrophotometer within 5 minutes at 450 nm with a reference
wavelength of 655 nm. Blank the plate reader according to the manufacturer’s instructions
using the blank wells.

OPTIONAL – Calculation of results using the standard curve
If you have generated a standard curve using Active Motif’s recombinant p53 protein, average
the duplicate readings for each standard, control, and sample and subtract the optical density(OD) obtained from the zero standard.
Plot the OD for the standards against the quantity (ng/well) of the standards and draw the best
fit curve. The data can be linearized using log/log paper and regression analysis may also be
applied.
To quantify the amount of p53 in the samples, find the absorbance value for the samples on the
y-axis and extend a horizontal line to the standard curve. At the intersection point extend a vertical line to the x-axis and read the corresponding standard value. Note: If the samples have been
diluted, the value read from the standard curve must be multiplied by the dilution factor.
p53 TransAM Assay
p53 Protein @ 0.3125 - 2.5 ng/well

0.125

y = 0.042x + 0.002 r = 0.998

0.1

A450

Example curve:
The following standard curve
is provided for demonstration
only. A standard curve should
be made every time an experiment is performed.

0.075
A450

0.05
0.025
0

0

0.5

1

1.5

2

2.5

p53 Recombinant Protein (ng)www.activemotif.com

113

Preparation of Nuclear Extract
For your convenience, Active Motif offers a Nuclear Extract Kit (Cat. Nos. 40010 & 40410). This
kit contains buffers optimized for use in TransAM Kits, which serves to reduce inconsistencies in
the assay that may arise from using homemade or other buffers. If you prefer to make your own
buffers, please refer to the following protocol.
This procedure can be used for a confluent cell layer of 75 cm2 (100-mm dish). The yield isapproximately 0.5 mg of nuclear proteins for 107 cells.
1.

Wash cells with 10 ml of ice-cold PBS/PIB.

2.

Add 10 ml of ice-cold PBS/PIB and scrape the cells off the dish with a cell lifter. Transfer thecells into a pre-chilled 15 ml tube and spin at 300 x g for 5 minutes at 4°C.

3.

Resuspend the pellet in 1 ml of ice-cold HB buffer by gentle pipetting and transfer the cells
into a pre-chilled 1.5 ml tube.

4.

Allow the cells to swell on ice for 15 minutes.

5.

Add 50 µl 10% Nonidet P-40 (0.5 % final) and mix by gentle pipetting.

6.

Centrifuge the homogenate for 30 seconds at 4°C in a microcentrifuge.

7.

Resuspend the nuclear pellet in 50 µl Complete Lysis Buffer and rock the tube gently on
ice for 30 minutes on a shaking platform.

8.

Centrifuge for 10 minutes at 14,000 x g at 4°C and save the supernatant (nuclear cell
extract). Aliquot and store at –80°C. Avoid freeze/thaw cycles.

9.

Determine the protein concentration of the extract by using a Bradford-based assay.

10X PBS
0.1 M phosphate buffer, pH 7.5
1.5 M NaCl
27 mM KCl

For 250 ml, mix:
3.55 g Na2HPO4 + 0.61 g KH2PO4
21.9 g
0.5 g

Adjust to 250 ml with distilled water. Prepare a 1X PBS solution by adding 10 ml 10X PBS to 90
ml distilled water. Sterilize the 1X PBS by filtering through a 0.2 µm filter. The 1X PBS is at pH 7.5.
Store the filter-sterilized 1X PBS solution at 4°C.
PIB (Phosphatase Inhibitor Buffer)
125 mM NaF
250 mM β-glycerophosphate
250 mM para-nitrophenyl phosphate (PNPP)
25 mM NaVO3

For 10 ml, mix
52 mg
0.55 g1.15 g
31 mg

Adjust to 10 ml with distilled water. Mix the chemicals by vortexing. Incubate the solution at 50ºC
for 5 minutes. Mix again. Store at –20°C.

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12PBS/PIB
Prior to use, add 0.5 ml of PIB to 10 ml of 1X PBS.
HB (Hypotonic Buffer)
20 mM Hepes, pH 7.5
5 mM NaF
10 µM Na2MoO4
0.1 mM EDTA

For 50 ml, mix
0.24 g
12 mg
5 µl of a 0.1 M solution
10 µl of a 0.5 M solution

Adjust pH to 7.5 with 1 N NaOH. Adjust volume to 50 ml with distilled water. Sterilize by filtering
through a 0.2 µm filter. Store the filter-sterilized solution at 4°C.

References
1.
2.
3.

Vousden K. (2000) Cell 103: 691-4.
Hupp T. R., Lane D. P. and Ball K. L. (2000) Biochem. J. 352: 1-17.
Kaghad M., Bonnet H., Yang A., Creancier L., Biscan J-C., Valent A., Minty A., Chalon P.,
Lelias J-M., Dumont X., Ferrara P., McKeon F. and Caput D. (1997) Cell 90: 809-19.
4. Yang A., Kaghad M., Wang Y., Gillett E., Fleming M. D., Dotsch V., Andrews N. C., Caput D.
and McKeon F. (1998) Mol. Cell 2: 305-16.
5. Yang A., Kaghad M., Caput D. and McKeon F. (2002) Trends in Genetics 18: 90-5.
6. Hollstein M., Hergenhahn M., Yang Q., Bartsch H., Wang Z-Q. and Hainaut P. (1999) Mutat.
Res. 431: 199-209.
7. El-Deiry W.S., Kern S.E., Pietenpol J.A., Kinzler K.W. and Vogelstein B. (1992) Nat. Genet. 1:
45-9.
8. Ashcroft M. and Vousden K. H. (1999) Oncogene 18: 7637-43.
9. Roth J., Dobbelstein M., Freedman D. A., Shenk T., Levine A. J. (1998) EMBO J. 17: 554-64.
10. Gottifredi V. and Prives C. (2001) Science 292: 1851-2.
11. Renard P., Ernest I., Houbion A., Art M., Le Calvez H., Raes M. and Remacle J. (2001)
Nucleic Acids Res. 29: (4) e21.

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13

Appendix
Section A. Troubleshooting Guide
PROBLEMPOSSIBLE CAUSE

RECOMMENDATION

No signal or weak signal
in all wells

Omission of key reagent

Check that all reagents have been addedin the correct order

Substrate or conjugate is nolonger active

Test conjugate and substrate for activity

Enzyme inhibitor present

Sodium azide will inhibit the peroxidase
reaction, follow our recommendations to
prepare buffers

Plate reader settings not optimal

Verify the wavelength and filter settings in
the plate reader

Incorrect assay temperature

Bring substrate to room temperature

Inadequate volume ofDeveloping Solution

Check to make sure that correct volume
is delivered by pipette

Developing time too long

Stop enzymatic reaction as soon as the
positive wells turn medium-dark blue

Concentration of antibodies
too high

Increase antibody dilutions

Inadequate washing

Ensure all wells are filled with Wash Buffer
and follow washing recommendations

High background in all wells

Uneven color development

High background in sample wells

No signal or weak signal insample wells

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Incomplete washing of wells
Ensure all wells are filled with Wash Buffer
and follow washing recommendations
Well cross-contamination

Follow washing recommendations

Too much nuclear extract per well

Decrease amount of nuclear extract down to
1-2 µg/well

Concentration of antibodies
too high

Perform antibody titration to determine
optimal working concentration. Start using
1:1000 for primary antibody and 1:5000 for thesecondary antibody. The sensitivity of theassay will be decreased

Not enough nuclear extract per well

Increase amount of nuclear extract not toexceed 40 µg/wellp53 is poorly activated orinactivated in nuclear fractions

Perform a time course for p53 activationin the studied cell line

Extracts are not from humanoriginPerform study with a human model

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Technical Services
If you need assistance at any time, please call or send an e-mail to Active Motif Technical Service
at one of the locations listed below.

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Toll free:Direct:Fax:
E-mail:Active Motif Europe
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E-mail:877.222.9543
760.431.1263
760.431.1351
tech_service@activemotif.com
0800/169 31 47
0800/90 99 79
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+32 (0)2 653 0050
eurotech@activemotif.com

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Fax: +81 (0)3 5261 8733
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