BIOL 2021 Lecture Notes - Lecture 5: Atp-Binding Cassette Transporter, Multiple Drug Resistance, Electrochemical Gradient
7 Apr 2016
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19. 1. 16 (look at the membrane sheet on moodle) Contributes to 10% to membrane potential = electrogenic. Atp binding cassette use atp pump small molecules out of cells (sometimes ions) Transports amino acids, polysaccharides, peptides, organic molecules. Conformational change due to binding hydrolysis also causes the next conformational change. Ex: useful for drug resistance, pump hydrophobic molecules out (mdr multiple drug resistance and protein= p-glycoprotein) Cancer cells can over express mdr pump out drugs resistance. Channel types: gap junctions porins, large pores, little selectivity. Cell to-cell or organelle-to-cytosol: aquaporins water channels (most cells don"t need water channels) Some cells need to transport water and it is not flowing as fast as required. Ex: fig 11-19: kidney/exocrine cells (epithelial cells) need the movement of water (not ions) in the cell: ion channels (fig 11-21) Mechanism: form a narrow pore, which is hydrophilic inside.
