Methylation and proteolysis are essential for efficient membrane binding of prenylated p21K-ras(B).
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.
Hancock
J F
JF
Department of Haematology, Royal Free Hospital School of Medicine, London, UK.
Cadwallader
K
K
Marshall
C J
CJ
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004285:Dogs; D004952:Esters; D007700:Kinetics; D008715:Methionine / Q000378:metabolism; D008745:Methylation; D008798:Mevalonic Acid / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D010179:Pancreas / Q000378:metabolism; D011485:Protein Binding; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism
D004952:Esters; D012333:RNA, Messenger; D008715:Methionine; D016283:Proto-Oncogene Proteins p21(ras); D008798:Mevalonic Acid