BIOL 2021 Chapter Notes - Chapter 13.4: Gtpase, Cytosol, Organelle
11 Mar 2018
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Ra(cid:271) proteins & pro(cid:272)ess: rab proteins important for specification of vesicle transport, also monomeric gtpases like coat-recruitment gtpase. It"s bound to rab-gdp dissociation inhibitor (gdi) that keeps soluble in cytosol: rab+gtp is active state. They"re associated w/ membrane of organelle or transport vesicle: membrane-bound rab-gefs activate rab proteins. Once gtp-bound, rab binds to other proteins, called rab effectors: rab proteins have conserved structure, but structure & function of rab effectors varies greatly. Active rab5-gtp is anchored to membrane & recruits more gef. Rab5 has pi3-kinase, which converts pi to pi(3)p, which binds to rab-effectors & stabilizes local membrane attachment. Rab5 membrane domains receives incoming endocytic vesicles from plasma membrane. Rab cascades can change identity of organelle: rab domains can be disassembled & replaced by different domains by rab cascade, rab cascades changes the membrane dynamics- changing incoming & outgoing traffic. Figure 13-16 tethering of a transport vesicle to target membrane.
