Carboxy-terminal CVLS-sequence-specific protein farnesyltransferase from the eyes of the shrimp Penaeus japonicus: Purification and characterization

Protein farnesyltransferase from the eyes of Penaeus japonicus farnesylates predominantly H-ras-specific carboxyl termini, with the sequence CVLS, but-not; the K-ras-specific sequence CVIM or the protein geranylgeranyltransferase-specific sequence CAIL. The purified protein farnesyltransferase from shrimp was found by immunoblotting and polyacrylamide gel electrophoresis under denaturing conditions to consist of subunits of Mr 49,000 and Mr 48,000. Since the active protein farnesyltransferase was found to have a relative mass of 100,000, the purified enzyme was deduced to be a heterodimer. The enzyme had an optimal pH of 6 and a K-m of 14 +/- 1 mu M with the synthetic peptide RTRCVLSH as the substrate. The enzyme was activated by Mn++ and Mg++ but inhibited by Ca++ ions. (C) 1996 wiley-Liss, Inc.