Characterization of Normal and Mutant Human Kirsten-ras(4B) p21 and of the Catalytic Domain of GAP
Point mutations in the Harvey-, N and Kirsten-ras genes are associated with 20–30% of human tumours1. Kirsten-ras is the gene most frequently activated in tumours. Certain tumour types contain high frequencies of K-ras mutation, for example colorectal (c. 50%) and pancreatic (>95%) tumours2–4. The high incidence of K-ras mutations in clinically important tumours makes the K-ras gene product of particular interest as a target for the discovery of potentially highly selective anti-tumour agents. Hitherto, biochemical studies on the ras proteins has focused on the products of the H- and N-ras genes. The product of the viral Kirsten-ras gene has been studied but it is the counterpart of a rare transcript of the cellular K-ras gene (transcript 2A or 4A). The commonly occuring form of K-ras (2B or 4B) expressed in human cells differs from the 4A transcript in having a lysine-rich C-terminus terminus, which is not modified by palmitoylation5.
KeywordsPurine Nucleoside Phosphorylase Fluorimetric Assay Immunoaffinity Purification ompT Protease Relative Binding Constant
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