Study Human Chemokine Receptor Figure 3. Selection of E.coli host strains and media for inducible expression of hCRs. A) Screening of E.coli strains and media for pEXP- hCRs. Each of pEXP-hCRs was transformed into all 5 E.coli strains: BL21, C41, C43, C41-pLysS and C43-pLysS, and spread on LB-agar plates (I), LB-agar- IPTG plates (II), TB-agar-IPTG plates (III) and 2YT-agar-IPTG plates (IV) for colony analysis. B) L-arabinose induction pBAD-hCRs for E.coli strain Top10. LB-agar plates without (2) and with (+) L-arabinose (0.05%) were used. C) Growth conditions of pBAD-hCRs in Top10 in the presence of inducer. Cell culture density at 600 nm (OD600) after indicated induction time, 3.5 hours, 6.5 hours, 10.5 hours and 24 hours, was measured. doi:10.1371/journal.pone.0004509.g003 PLoS ONE | www.plosone.org 5 February 2009 | Volume 4 | Issue 2 | e4509