BIOL 3051 Chapter Notes - Chapter 11.3: Tetraethylammonium, Trypsin, Cardiac Muscle Cell
24 Apr 2020
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Structure of k+ channels: alpha subunit is main, ion conduction unit, beta unit: provides regulatory function. Could be cytoplasmic or tm, modulates channel properties & function. Mechanism of ion selectivity by k channel: selectivity filter has tvgtg motif, w/en o atoms that interaction w/k+ ion. In central cavity k+ is hydrated shell . k+ ions dehydrated before entering pore b/c narrow: 2k+ ions/pore. 4 possible k+ spaces (1,3 or 2,4: motif v/o atom interact w/de-hydrated k+. Pore is stabilizing k+ to allow selective ion conduction. 2 basic mechanism of kv inactivation: n-type: fast, c-type: slow, n-type kv inactivation. Fast inactivation w/ peptide folded into ball. Ball could be attached to alpha or beta unit. N-type blocks intracellular domain: c-type k+ inactivation. Slow inactivation by transition to non-conducting state at extracellular end after prolonged activation. Quaternary ammonium (qa)- block k+ channel: k+ channel blocked by qa (ex: tetraethylammonium,
