TOOLS FOR THE PRODUCTION AND PURIFICATION OF FULL-LENGTH, N-TERMINAL OR C-TERMINAL P-32 LABELED PROTEIN, APPLIED TO HIV-1 GAG AND REV

We have constructed two new vectors for the production of foreign proteins in Escherichia coli. The vectors, pGEX-GTH and pET-HTG, produce protein fused to glutathione S-transferase (GST) at the N- and C-termini, respectively, allowing one-step purification on glutathione-Sepharose. Furthermore, they carry the recognition sequence (RRASV) for the catalytic subunit of cAMP-dependent heart muscle kinase (HMK) at the terminus distal to the GST tag, enabling specific P-32 labeling in vitro. By positioning the GST and HMK sequences at opposite ends of the introduced gene, only full-length fusion protein becomes radiolabeled after purification. Avoiding the labeling of shorter fusion protein species, often observed in bacterial expression of foreign genes, is particularly important for a number of different purposes, including protein mobility shift analysis and protein footprinting technology.