Two large classes of GTPase switch proteins-

Heterotrimeric G proteins

Monomeric G proteins

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#Unit 4. Cell Communication and Cell Signaling

Insulin stimulated activation of PKB promotes rapid activation of glycogen synthase and glycogen synthesis

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#Unit 4. Cell Communication and Cell Signaling

Mating pathway in the yeast S. cerevisiae, is a MAP kinase cascade which linked to GPCRs.

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#Unit 4. Cell Communication and Cell Signaling

Two mating types of yeast cells are: 

1. a 

2. α

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#Unit 4. Cell Communication and Cell Signaling

Haploid yeast cells secrete protein signals known as pheromones, which induce mating between opposite mating types.

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#Unit 4. Cell Communication and Cell Signaling

An a haploid cell secretes the a mating factor and has GPCRs for the α factor on its cell surface; an α cell secretes the α factor and has GPCRs for the a factor.

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#Unit 4. Cell Communication and Cell Signaling

Activation of the MAP kinase pathway by either the a or the α GPCRs induces transcription of genes that inhibit progression of the cell cycle