BIOLOGY 2D03 Lecture Notes - Signal Transduction, Transcytosis, Gtpase
28 Jan 2013
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Document Summary
Endocytosis: helps to maintain cell size/volume via cell membrane for nutrition, defense, and homeostasis bacteria/viruses take advantage of it. Phagocytosis attachment: receptor mediated not energy dependent engulfment: energy dependent actin-based rearrangement around bacteria ends in membrane fusion also involves unconventional myosin motors degradation: phagosome fuses with lysosome. Killing strategies : oxygen dependent use of hydrogen peroxide, oxygen independent enzymatic (degrade bacterial walls/membranes) Subversion fusion inhibition hydolase resistance intracellular survival escape. Overview: small particle internalization binding concentrates the ligand greater efficiency/selectivity similar machinery as used in exocytosis. Ldlr defects cytoplasmic tail mutation that prevents clustering does not affect ligand binding several kinds of endocytic signals; vary in distance from lipid bilayer. Types: constitutive receptors cluster w/out ligand binding induced activated by ligand binding tethered anchored to cytoskeleton slow endocytosis. Internalization clathrin mediated (also involved in lysosomal targeting during exocytosis) Triskelion ccv subunit; 3hc + 3lc various vesicle sizes (12 pentagons + various hexagons) form baskets spontaneously in vitro.
