Mammalian microsomal and soluble Ras-processing peptidase activities are distinct.
Microsomal and soluble peptidases from bovine liver and pig brain hydrolyze the farnesylated, Ras-based CAAX peptide [3H]Ac-fCVIM-OH. However, they differ in their sensitivity to substrate-based inhibitors, sulfhydryl and chelating agents, pH and ionic strength optima, and stability. The microsomal activity was exquisitely sensitive to the substrate-based inhibitor Boc-fC[CH2]VIM-OH, moderately sensitive to the sulfhydryl agent pCMB, but insensitive to NEM and the metal-chelating agent o-phenanthroline. The soluble activity was insentive to Boc-fC[CH2]VIM-OH, but very sensitive to pCMB, NEM and o-phenanthroline, suggesting it to be the previously reported (Biochem. Biophys. Res. Commun. 198, 787-794 (1994)) zinc metallopeptidase. The microsomal activity is most likely to be a cysteine peptidase involved in the post-translational processing of Ras proteins.
Hitz
A M
AM
Oncology Department, Roche Research Center, Nutley, NJ 07110, USA.
Georgopapadakou
N H
NH
D000818:Animals; D001921:Brain / Q000201:enzymology; D002417:Cattle; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008861:Microsomes / Q000201:enzymology*; D008862:Microsomes, Liver / Q000201:enzymology; D009994:Osmolar Concentration; D011499:Protein Processing, Post-Translational; D012995:Solubility; D013552:Swine; D018631:ras Proteins / Q000378:metabolism*
D003546:Cysteine Endopeptidases; D018631:ras Proteins