MOLECULAR-CLONING AND CHARACTERIZATION OF AN ISOPRENYLATED 67 KDA PROTEIN

The cDNA coding for a 67 kDa protein (p67) was isolated from a rat Sch wann cell library. A recombinant form of p67 expressed in bacteria was used to produce polyclonal anti-p67 antibodies. By immunoblot analysi s p67 was found to be expressed in most tissues and cell lines examine d. Inspection of the deduced amino acid sequence revealed a COOH-termi nal consensus sequence for isoprenylation. Consistent with this findin g, p67 was a substrate for isoprenylation in vitro by geranylgeranylpy rophosphate. p67 was associated predominantly with the particulate fra ction of rat smooth muscle cells. The rat p67 sequence was highly homo logous to a family of recently described human and mouse gamma-interfe ron inducible, guanine nucleotide binding proteins.