MCD BIO 165A Lecture Notes - Lecture 4: Cell Membrane, Opsin, Rhodopsin

• School: UCLA
• Department: Molecular, Cell, and Developmental Biology
• Course: MCD BIO 165A
• Professor: arispe

Document Summary

G protein-coupled receptors (gpcr) & 2nd messengers: gpcr/7-pass transmembrane receptors are the largest superfamily of proteins encoded by animal genomes. A group of proteins associated with plasma membrane; exists in either activated or inactivated form. Alpha/beta+gamma will bind to effector if they find one -> activation of other effectors is a matter of opportunity. If effe(cid:272)tor that (cid:272)a(cid:374) (cid:271)e a(cid:272)ti(cid:448)ated is(cid:374)"t prese(cid:374)t till g protei(cid:374) goes i(cid:374)a(cid:272)ti(cid:448)e agai(cid:374), it (cid:449)o(cid:374)"t (cid:271)e a(cid:272)ti(cid:448)ated. sometimes different ligands & receptors end up affecting same effector -> competition: deactivation of g protein. After effector generates reaction, camp level goes down -> alpha gtp switched to. Gdp -> g protein reassociates, back to inactive g protein: gpcr can be deactivated even when ligand still bound receptor phosphorylated -> arrestin binds receptor & prevents phosphatase from dephosphorylating it. Balance between activation & inactivation in every signaling cascade. (cid:449)hether it"s a(cid:272)ti(cid:448)e depe(cid:374)ds o(cid:374) its phosphor(cid:455)latio(cid:374) status & other signals.