ANAT 365 Lecture Notes - Lecture 19: Lipid Raft, Endosome, Tight Junction
19 Jul 2016
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Document Summary
2 diff environments on opposite sides of cell. Formation of tight junction & generation of polarity are coupled. 1: vectoral sorting, get into vesicle that knows which side to fuse with. 2: retention, send a protein to both side, but only stays on one side. Combination of 2 mechanisms for differential polarized sorting. Diff pathways, even for same protein or same cell. Destined for apical or basolateral membrane decision made at tgn. Sorting made at endosome b/w apical & basolateral. Go to basolateral first, endocytosed, apical machinery in endosome. Selective retention works for integral membrane proteins, but not for secreted proteins (once fused gone already) Ap1b (specific mu subunit) only in cells w/apical/basolateral polarity. If sorted to basolateral through dileucine, don"t need ap1b. Mutated ap1b: proteins w/tyrosine motif distributed equally b/w apical & basolateral. More than one way to get to basolateral. Apical protein + basolateral signal: sufficient to take to basolateral.
