BIOL 3051 Chapter Notes - Chapter 9.5: Arginine, Lysine, Potassium Channel
24 Apr 2020
School
Department
Course
Professor
Document Summary
Vgic have 3 main parts: voltage sensor. Voltage-sensing channels: full channels (k+, na+, ca2+) consist of 24 transmembrane domains. Via 4 subunits in k+; 1 continuous protein in na+ & ca2+ Na+/ca2+ channels have 4 domains w/6 transmembrane components: s4 contains voltage-sensing component w/ positive residues (arginine or lysine) Voltage sensing: 3 residues in voltage sensing domain (s4, region repelled towards ecf during depolarization. Implies that multiple voltage sensing domains must move before channel opens. All 4 vsds must be activated for channel opening. Na channel classification & structure: 9 isoforms of na+ channels, alpha subunit: contains transmembrane s1-s6 w/4 domains. S4 has (+) charged aa residues (arginine) at every 3rd position. Intracellular loop b/t domains 3-4 serves as inactivation gate. Folding of channel blocks pore from sustained depolarization of membrane: beta subunit. Dual functions: modulation of channel gating. With just alpha units, sodium channels will activate & inactive slowly than expected.
