BIO SCI D103 Lecture Notes - Lecture 16: Gs Alpha Subunit, Adenylyl Cyclase, Cholera Toxin
26 Nov 2018
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It can"t sense a direction and migrates aimlessly: small thing protrusions stay more in a ball shape, rac: front end: protrusion - front end, rho: backend - actin myosin contraction, both inhibit one another. On - gtp: gtpases serve as molecular timers on #1 ligand binds receptor, increasing affinity for a specific g alpha. #3 gtp-bound alpha subunit dissociates from the receptor and g beta/gamma subunits bind to distinct effectors. #5 g alpha hydrolyzes gtp = inactiviating the protein. #6 g alpha reassociates w/ beta/gamma, effector ceases activity. #7 desensitization of the receptor can occur by grk phosphorylation. If g beta / gamma was removed from k+ channels, it will shut it off: cyclic nature of g alpha that controls whether k+ channels are one or off. It is destroyed; if you degrade it in the lysosome, it is no longer there and is irreversible: a, c, d, e, the receptor is still there.
