Protein: Polyubiquitin 3 [Cleaved into: Ubiquitin] (Q1EC66)
Organism: Arabidopsis thaliana (Mouse-ear cress)
Function: Ubiquitin exists either covalently attached to another protein, or free (unanchored). When covalently bound, it is conjugated to target proteins via an isopeptide bond either as a monomer (monoubiquitin), a polymer linked via different Lys residues of the ubiquitin (polyubiquitin chains) or a linear polymer linked via the initiator Met of the ubiquitin (linear polyubiquitin chains). Polyubiquitin chains, when attached to a target protein, have different functions depending on the Lys residue of the ubiquitin that is linked: Lys-11-linked is involved in ERAD (endoplasmic reticulum-associated degradation) and in cell-cycle regulation; Lys-29-linked is involved in lysosomal degradation; Lys-33-linked is involved in kinase modification; Lys-48-linked is involved in protein degradation via the proteasome; Lys-63-linked is involved in endocytosis, and DNA-damage responses. Linear polymer chains formed via attachment by the initiator Met lead to cell signaling. Ubiquitin is usually conjugated to Lys residues of target proteins, however, in rare cases, conjugation to Cys or Ser residues has been observed. When polyubiquitin is free (unanchored-polyubiquitin), it also has distinct roles, such as in activation of protein kinases, and in signaling (By similarity).
Subcellular location: Cytoplasm {ECO:0000250}. Nucleus {ECO:0000250}.
Sequence: MQIFVKTLTGKTITLEVESSDTIDNVKAKIQDKEGIPPDQQRLIFAGKQLEDGRTLADYNIQKESTLHLVLRLRGGMQIFVKTLTGKTITLEVESSDTIDNVKAKIQDKEGIPPDQQRLIFAGKQLEDGRTLADYNIQKESTLHLVLRLRGGMQIFVKTLTGKTITLEVESSDTIDNVKAKIQDKEGIPPDQQRLIFAGKQLEDGRTLADYNIQKESTLHLVLRLRGGMQIFVKTLTGKTITLEVESSDTIDNVKAKIQDKEGIPPDQQRLIFAGKQLEDGRTLADYNIQKESTLHLVLRLRGGSF
InterPro domains: - IPR000626: Ubiquitin-like domain (domain) [1-304]
- IPR029071: Ubiquitin-like domain superfamily (homologous_superfamily) [1-304]
- IPR050158: Ubiquitin and ubiquitin-like (family) [153-230]
- IPR019956: Ubiquitin domain (domain) [11-74]
- IPR019954: Ubiquitin conserved site (conserved_site) [27-280]
Interaction partners: - Protein NBR1 homolog
- E3 ubiquitin-protein ligase PRT1
- E3 ubiquitin-protein ligase UPL4
- E3 ubiquitin-protein ligase UPL3
- 26S proteasome non-ATPase regulatory subunit 2 homolog A
- Small ribosomal subunit protein eS1z
- Small ribosomal subunit protein uS9x
- Large ribosomal subunit protein uL5z
- Proteasome subunit beta type-1
- Small ribosomal subunit protein eS7x
Gene Ontology annotations:
Molecular Function (MF): GO:0003674 (molecular function), GO:0005488 (binding), GO:0097159 (organic cyclic compound binding), GO:1901363 (heterocyclic compound binding), GO:0003676 (nucleic acid binding), GO:0003723 (RNA binding), GO:0003729 (mRNA binding)
Biological Process (BP): GO:0008150 (biological process), GO:0008152 (metabolic process), GO:0009987 (cellular process), GO:0044238 (primary metabolic process), GO:0044237 (cellular metabolic process), GO:0071704 (organic substance metabolic process), GO:0009056 (catabolic process), GO:0006807 (nitrogen compound metabolic process), GO:1901564 (organonitrogen compound metabolic process), GO:0019538 (protein metabolic process), GO:1901575 (organic substance catabolic process), GO:0044260 (cellular macromolecule metabolic process), GO:0043170 (macromolecule metabolic process), GO:0044248 (cellular catabolic process), GO:0009057 (macromolecule catabolic process), GO:1901565 (organonitrogen compound catabolic process), GO:0006508 (proteolysis), GO:0044265 (cellular macromolecule catabolic process), GO:0030163 (protein catabolic process), GO:0043632 (modification-dependent macromolecule catabolic process), GO:0051603 (proteolysis involved in protein catabolic process), GO:0019941 (modification-dependent protein catabolic process), GO:0006511 (ubiquitin-dependent protein catabolic process)
Cellular Component (CC): GO:0005575 (cellular component), GO:0110165 (cellular anatomical entity), GO:0005737 (cytoplasm), GO:0005829 (cytosol), GO:0005622 (intracellular anatomical structure)