BIOL 4320 Lecture 7: Notes Exam 2 (Lectures 7-12)
16 Jun 2016
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Intermediate-sized gtpases such as elongation factors tu (ef-tu) and g (ef-g) All share: canonical guanine nucleotide-binding domain and subject to so-called gtpase cycle. Activated by gefs or gnrps which accelerate the dissociation of guanosine 5"- diphosphate (gdp) from the nucleotide-binding site, resulting in replacement by guanosine. Gaps help turn them off (1) heterotrimeric gtp-binding proteins. Signals bind and activate 7 transmembrane-helix receptors these activate intracellular membrane-associated heterotrimeric gtp-binding proteins which are mediators/amplifiers downstream effector molecules. Gq: activating phospholipase c (lipase catalyzes hydrolysis of fats) Exception: gh: phospholipase c activator that has unconvential gtp-binding site. Alpha exchanges gdp for gtp, ga-gtp dissociates from gby (7 transmembrane-helix receptors act as gefs for ga subunits) they can independently interact with downstream effector macromolecules. Al ga subunits are myriostoylated at the n-terminal glycine residue. All ga subunits are transiently palmitoylated via a labile thioester bond (c-s-co-c) near the. N-terminus (reversibility provides extra means of cellular localization and signal modulation)
