植物激素作用中的Ｇ蛋白调节

Guanine nucleotide-binding proteins known as G proteins or GTPases are universal molecularswitches that play a pivotal role in signal transduction. Signal transducing GTPases include het-erotrimeric G proteins composed of Ga, Gl3 and GT and monomeric small GTPases. Small GTPasesare related to the ct subunit of heterotrimeric G proteins but differ from heterotrimerie G proteins inthe mechanisms by which they are regulated by upstream factors as well as those by which they acti-vate downstream targets (Yang, 2002). There are two types of G proteins cycle between the activeGTP-bound and inactive GDP-bound forms through GDP-GTP exchange and GTP hydrolysis, respec-tively.

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