Relative steady-state expression of the different post-translational products of p21-H-ras from normal rat tissues. A...

Proteins extracts from rat cell lines or tissues expressing normal or activated c-H-ras genes, or normal N-ras gene were submitted to westernblot analysis with an anti-H, K, N p21-ras antibody. This showed that p21-H-ras products resolved into four spots (a, b, c, d) that are readily distinguishable from the normal p21-N-ras products (spots e, f, g), and also from two other products (spots a', b') present in extracts from cells which overexpress a Val12-mutated H-ras gene. Considering metabolic isotopic labeling and cell fractionation, we were able to establish the correspondance of spots a, b, c, d with the known steps of the sequential post-translational processing (farnesylation, further carboxymethylation and ultimate palmitoylation) of p21-H-ras. The palmitoylated product predominates in normal brain and still more in normal adult liver tissues, whereas its relative level decreases in proliferating liver cells.