Signalling in the nervous system, rhythmic beating of the heart, muscle excitation, and secretion by endocrine and epithelial cells are some of the important processes that are largely accomplished by ion channels. These molecules are ion selective pores in cell membranes that open and close in response to a wide variety of stimuli, such as membrane voltage, neurotransmitter molecules and intracellular messengers. Ions flowing through these channels transmit information either by directly acting as intracellular messengers themselves or by changing the membrane voltage. An important goal of modern neurobiology and physiology is to understand the molecular mechanisms whereby channel molecules change their conformation in response to voltage. The sensitivity to voltage of channel molecules and the time course of their response to changes in voltage largely determine the electrical properties of a given cell. The elucidation of these voltage-dependent gating mechanisms is important to our understanding of basic cellular mechanisms and their dysfunction during such pathological states as cardiac arrhythmias, periodic paralysis, and epilepsy. The understanding of molecular mechanisms of channel gating will require a combination of electrophysiological, molecular, and structural techniques. This proposal focuses on the molecular mechanisms of potassium channel gating. Single-channel, macroscopic and gating current measurements will be made on Shaker and related potassium channels expressed in Xenopus oocytes or cultured cell lines. These measurements of channel gating properties will be performed on channels that have been altered in specific ways by site-directed mutagenesis. Functional alterations that result from defined structural changes will be characterized to understand the conformational changes involved in voltage- dependent channel opening and in channel inactivation. The interaction between permeant ions and the conformational changes involved in gating and the regulation of gating by protein phosphorylation will also be elucidated.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS023294-11
Application #
2264771
Study Section
General Medicine B Study Section (GMB)
Project Start
1992-07-01
Project End
1999-06-30
Budget Start
1995-07-01
Budget End
1996-06-30
Support Year
11
Fiscal Year
1995
Total Cost
Indirect Cost
Name
Stanford University
Department
Biology
Type
Schools of Medicine
DUNS #
800771545
City
Stanford
State
CA
Country
United States
Zip Code
94305
Brenner, R; Jegla, T J; Wickenden, A et al. (2000) Cloning and functional characterization of novel large conductance calcium-activated potassium channel beta subunits, hKCNMB3 and hKCNMB4. J Biol Chem 275:6453-61
Middendorf, T R; Aldrich, R W; Baylor, D A (2000) Modification of cyclic nucleotide-gated ion channels by ultraviolet light. J Gen Physiol 116:227-52
Middendorf, T R; Aldrich, R W (2000) Effects of ultraviolet modification on the gating energetics of cyclic nucleotide-gated channels. J Gen Physiol 116:253-82
Horrigan, F T; Aldrich, R W (1999) Allosteric voltage gating of potassium channels II. Mslo channel gating charge movement in the absence of Ca(2+). J Gen Physiol 114:305-36
Kanevsky, M; Aldrich, R W (1999) Determinants of voltage-dependent gating and open-state stability in the S5 segment of Shaker potassium channels. J Gen Physiol 114:215-42
Ledwell, J L; Aldrich, R W (1999) Mutations in the S4 region isolate the final voltage-dependent cooperative step in potassium channel activation. J Gen Physiol 113:389-414
Ogielska, E M; Aldrich, R W (1999) Functional consequences of a decreased potassium affinity in a potassium channel pore. Ion interactions and C-type inactivation. J Gen Physiol 113:347-58
Horrigan, F T; Cui, J; Aldrich, R W (1999) Allosteric voltage gating of potassium channels I. Mslo ionic currents in the absence of Ca(2+). J Gen Physiol 114:277-304
Smith-Maxwell, C J; Ledwell, J L; Aldrich, R W (1998) Uncharged S4 residues and cooperativity in voltage-dependent potassium channel activation. J Gen Physiol 111:421-39
Ogielska, E M; Aldrich, R W (1998) A mutation in S6 of Shaker potassium channels decreases the K+ affinity of an ion binding site revealing ion-ion interactions in the pore. J Gen Physiol 112:243-57

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