GTPase's

GTPase

small, catalytic proteins that have the ability to bind guanine nucleotides

GTPase when bound to GTP is what (inactive or active)

active conformation

GTPase when bound to GDP is what (inactive or active)

inactive conformation

bound GTP is naturally hydrolyzed into what

GDP

GEFs

• guanine nucleotide exchange factors

• precisely controls GTPase activation

• stimulate the exchange of GDP for GTP

  • pushes GTPases into their active conformation

GAPs

• GTPase activating proteins

• stimulate the rapid hydrolysis of GTP to GDP

  • pushes GTPases into their inactivate conformation

GDIs

• guanosine dissociation inhibitors

• bind to GTPases and prevent the release of GDP

  • maintain GTPases in their inactive conformation

GTPase switch diagram/picture

what are the two types of G-proteins

monomeric and heterotrimeric/trimeric

different types of monomeric GTPases

• Ras

• Rho

• ARF

• Rab

• Ran

G-proteins

• trimeric GTPases

• 3 subunits: alpha, beta, and gamma

• alpha subunit behaves like a monomeric GTPase

• inactive when bound to GDP

• active when bound to GTP

what is Gs

• a stimulatory G-protein

• stimulates an effector protein

what is a Gi

• an inhibitory G-protein

• inhibits an effector protein

what are the 3 classes of transmembrane receptors

• gated ion channels

• enzyme-couple receptors

• G-protein coupled receptors

dimer signaling molecules are what

stronger than single molecule signaling

what is cross-phosphorylation

when activated kinase domains phosphorylate and increase each other’s activity