Explain How Mutations in the Following Proteins Might Result in Either

Essay

Explain how mutations in the following proteins might result in either loss of responsiveness to a given hormone or production of a continuous signal even in the absence of the hormone: (a) a mutation in the regulatory (R) subunit of cAMP-dependent protein kinase, making R incapable of binding to the catalytic (C) subunit; (b) a mutation in a growth factor receptor with protein kinase activity; (c) a defect in a G protein that renders the GTPase activity inactive.