A number of mutations have been described in G proteins that have profound effects on their activity. For example, some mutations greatly increase the affinity of the G protein for GDP making it very difficult to be exchanged for GTP. Other mutations prevent the hydrolysis of GTP to GDP. For each of the following choices, indicate which of the following mutations is responsible: High GDP affinity RAS mutant, Hydrolysis-deficient RAS mutant, or Neither.
a. Hydrolysis-deficient RAS mutant
b. Neither
c. High GDP affinity RAS mutant