A Ligand-gated Dephosphorylate Chan Regulation of gating in ion channels. Several types of gating are shown for ion channels A)Ligand-gated channels open in response to ligand D Stretch or pressure-gated bi Inding Stretch B)Protein phosphorylation or dephosphory lation regulate opening and closing of some ion channels C)Changes in membrane potential alter channel openings D)Mechanical stretch of the membrane results in channe Cytoskeleton opening bysiology:www.accessmedicine.con
Regulation of gating in ion channels. Several types of gating are shown for ion channels. A) Ligand-gated channels open in response to ligand binding. B) Protein phosphorylation or dephosphorylation regulate opening and closing of some ion channels. C) Changes in membrane potential alter channel openings. D) Mechanical stretch of the membrane results in channel opening
B C D Source: Barrett KE, Barman SM, Boitano S, Brooks HL Ganong'sReviewofMedicalPhysiologywww.accessmedicine.com Copyright c The McGraw-Hill Companies, Inc. All rights reserved. Different ways in which ion channels form pores. Many K channels are tetramers A), with each protein subunit forming part of e channe In ligand- gated cation and anion channels b) such as the acetylcholine receptor. five identical or very similar subunits form the channe Cl channels from the CiC family are dimers c), with an intracellular pore in each subunit Aquaporin water channels(D)are tetramers with an intracellular channel in each subunit
Different ways in which ion channels form pores. Many K+ channels are tetramers A), with each protein subunit forming part of the channel. In ligand-gated cation and anion channels B) such as the acetylcholine receptor, five identical or very similar subunits form the channel. Cl- channels from the ClC family are dimers C), with an intracellular pore in each subunit. Aquaporin water channels (D) are tetramers with an intracellular channel in each subunit
Extracellular Cytoplasmic COOH Diagrammatic representation of the Ca2+ cha pore-forming subunits of three ion channels The a subunit of the Nat and Ca2+ channels traverse the membrane 24 COOH times in four repeats of six membrane spanning units. Each repeat has a"P loop between membrane spans 5 and 6 that does not traverse the membrane K+ channel These p loops are thought to form the pore. Note that span 4 of each repeat is colored in red, representing its net“+” charge. The k channel has only a single repeat of the six spanning regions and P COOH loop. Four K subunits are assembled for a functional K channel anong'sReviewofMedicalPhysiologywwrw.accessmedicine.com opyright s The McGraw-Hill Companies, Inc. All rights reserved
Diagrammatic representation of the pore-forming subunits of three ion channels. The α subunit of the Na+ and Ca2+ channels traverse the membrane 24 times in four repeats of six membranespanning units. Each repeat has a “P” loop between membrane spans 5 and 6 that does not traverse the membrane. These P loops are thought to form the pore. Note that span 4 of each repeat is colored in red, representing its net “+” charge. The K+ channel has only a single repeat of the six spanning regions and P loop. Four K+ subunits are assembled for a functional K+ channel
Three types of passive, non-coupled transport through integral membrane proteins A PORE(NON-GATED CHANNEL B CHANNEL(GATED PORE) sPores are conduits Channels are conduits that are gated by a"door. that are always open Channel is closed Channel is Extracellular Cy space
Three types of passive, non-coupled transport through integral membrane proteins
C CARRIER 2 The carrier is open X enters from outside and to the outside binds at a binding site Carriers are conduits that are gated by two 8 doors" that are never open at the same time Binding 3 site The outer gate closes and X becomes occluded, still attached to its binding site. 6 The outer gate closes, occluding an empty cycle can also flow in reverse orde 4 X exits and enters the The inner gate open inside of the cell with X still bound