THE CELL
CELL COMMUNICATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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kinase activity and the addition of a tyrosine
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GTPase activity and hydrolysis of GTP to GDP
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adenylyl cyclase activity and the conversion of cAMP to AMP
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Detailed explanation-1: -The conversion from the GTP-to the GDP-bound form is mediated by the intrinsic GTPase activity of Ras, a reaction that is accelerated by the binding of the GTPase-activating-protein (GAP) (4, 5).
Detailed explanation-2: -Conversion of GDP into GTP by nucleoside diphosphate kinase on the GTP-binding proteins. A direct interaction of alpha beta gamma trimeric GTP binding proteins (G proteins; G0 and Gs) with nucleoside diphosphate kinase (NDP kinase) was investigated with homogeneously purified proteins.
Detailed explanation-3: -GTPase-activating proteins (GAPs) regulate heterotrimeric G proteins by increasing the rates at which their subunits hydrolyze bound GTP and thus return to the inactive state. G protein GAPs act allosterically on G subunits, in contrast to GAPs for the Ras-like monomeric GTP-binding proteins.
Detailed explanation-4: -GTPase-activating proteins (GAPs) activate the intrinsic GTPase activity, catalyzing the hydrolysis of GTP into GDP. It is the interplay between the GTPases, the GEFs, and the GAPs that coordinates signal transduction regulated by GTPases (Fig. 6.1).