Methylation and proteolysis are essential for efficient membrane binding of prenylated p21K-ras(B).

Abstract

Plasma membrane targeting of p21K‐ras(B) requires a CAAX motif and a polybasic domain. The CAAX box directs a triplet of post‐translational modifications: farnesylation, proteolysis of the AAX amino acids and methylesterification. These modifications are closely coupled in vivo. However, in vitro translation of mRNA in rabbit reticulocyte lysates produces p21K‐ras(B) proteins which are arrested in processing after farnesylation. Intracellular membranes are then required both for proteolytic removal of the AAX amino acids and methylesterification of farnesylated p21K‐ras(B). Binding of p21K‐ras(B) to plasma membranes in vitro can then be shown to depend critically on AAX proteolysis and methylesterification since p21K‐ras(B) which is farnesylated, but not methylated, binds inefficiently to membranes.

Farnesylcysteine analogues inhibit store-regulated Ca2+ entry in human platelets: evidence for involvement of small GTP-binding proteins and actin cytoskeleton

“…We therefore investigated the effect of FTA on the association of Ras with membranes. Our results, in agreement with others [45,57], show that FTA impaired the membrane association of Ras stimulated by TG. Because methylation is the only reversible step of prenylation\methylation [24], FTA could exert its effect by inhibiting this process, thereby inhibiting the association of Ras proteins with membranes, which has been reported to be an important process for Ras activation [45].…”

“…Analysis of the farnesylated intermediate of Ras for its ability to associate with membranes showed that less than 20% of that intermediate associates with the membrane ; in contrast, after methylation the association was approx. 80% [57].…”

PostprenylationCAAXProcessing Is Required for Proper Localization of Ras but Not Rho GTPases

“…In contrast, farnesylated peptides were dependent on carboxyl methylation for efficient partitioning into liposomes. Similarly, methylation has been reported to enhance the membrane affinity of in vitro-translated K-Ras (Hancock et al, 1991a).…”

Protein Farnesyltransferase in Plants (Molecular Cloning and Expression of a Homolog of the [beta] Subunit from the Garden Pea)

“…Vol. 101, 1993 residues (AAX) of the protein substrate for FTase and GGTase I are removed, and the a-carboxyl group of the terminal Cys is methylated, whereas the isoprenoid moiety is linked to the Cys by a thioether bond (Kawata et al, 1990;Hancock et al, 1991a;Yamane et al, 1991).…”