本题目来源于试卷: Interaction & Interdependence C.4 Chemical Signaling，类别为 IB生物学
[单选题]
A signalling chemical i kehmd/a3;ul;s needed to activate the G kip*sw qttr xq+5/* ;is(/niwt7njt1+5 pp scprotein by binding to the G protein-coupled receptor/jpxtc; kswri w(s7q+p q 5+s*t 5p tni/1n*ti. What other substance is needed to activate the G protein?
A. GTP
B. cAMP
C. GDP
D. ATP
参考答案: A
本题详细解析:
A Choice A is correct because GTP, guanosine triphosphate, needs to bind with the G protein and replace the GDP to activate the G protein. Choice C is incorrect because GDP is attached to an inactive G protein, which is then replaced by GTP to activate the G protein. Choices B and D are incorrect because cAMP is the secondary messenger that gets formed from ATP in reactions that take place after the G protein is activated.
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