The long-term goal of this research is to elucidate the molecular and cellular mechanisms that ensure potassium (K+) channels assemble with the appropriate membrane-embedded regulatory subunits for proper physiological function. The KCNE regulatory subunits are a class of type 1 transmembrane peptides that co-assemble with tetrameric voltage-gated K+ channels, providing the electrical diversity needed to function in a wide-variety of cells and tissues. This proposal investigates KCNQ1-KCNE K+ channel complexes that enable potassium ingress into the endolymph, maintain salt and water homeostasis in intestinal epithelia, and generate the cardiac IKs current. There are three aims to this proposal: (1) We will establish assembly mechanisms for K+ channel-KCNE complexes with structurally different tetramerization domains and determine how the disease-associated mutations directly affect co-assembly. (2) We will determine the quaternary structures of misassembled K+ channel subunits in the endoplasmic reticulum. (3) We will determine whether KCNE subunits asymmetrically modulate the ion-conducting subunits using a combination of derivatized scorpion toxins and differentially-mutated KCNQ1 subunits.

Public Health Relevance

Potassium (K+) channels function as macromolecular protein complexes composed of membrane-embedded ion-conducting and regulatory subunits. Mutations that prevent the assembly, trafficking or function of these complexes give rise to neurological, cardiac, muscular, auditory, and respiratory diseases. By investigating the molecular and cellular mechanisms that ensure the assembly, trafficking and function of K+ channel complexes, we aim to understand how these proteins work in healthy individuals and provide alternative strategies for remedying those affected by channelopathies (ion channel-related diseases).

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM070650-08
Application #
8389665
Study Section
Neurotransporters, Receptors, and Calcium Signaling Study Section (NTRC)
Program Officer
Nie, Zhongzhen
Project Start
2005-04-01
Project End
2014-11-30
Budget Start
2012-12-01
Budget End
2013-11-30
Support Year
8
Fiscal Year
2013
Total Cost
$328,917
Indirect Cost
$128,967
Name
University of Massachusetts Medical School Worcester
Department
Biochemistry
Type
Schools of Medicine
DUNS #
603847393
City
Worcester
State
MA
Country
United States
Zip Code
01655
Zhang, Lejie; Bellve, Karl; Fogarty, Kevin et al. (2016) Fluorescent Visualization of Cellular Proton Fluxes. Cell Chem Biol 23:1449-1457
Kubat Öktem, Elif; Mruk, Karen; Chang, Joshua et al. (2016) Mutant SOD1 protein increases Nav1.3 channel excitability. J Biol Phys 42:351-70
Mruk, Karen; Kobertz, William R (2015) Bioreactive Tethers. Adv Exp Med Biol 869:77-100
Aromolaran, Ademuyiwa S; Subramanyam, Prakash; Chang, Donald D et al. (2014) LQT1 mutations in KCNQ1 C-terminus assembly domain suppress IKs using different mechanisms. Cardiovasc Res 104:501-11
Malaby, Heidi L H; Kobertz, William R (2014) The middle X residue influences cotranslational N-glycosylation consensus site skipping. Biochemistry 53:4884-93
Kobertz, William R (2014) Stoichiometry of the cardiac IKs complex. Proc Natl Acad Sci U S A 111:5065-6
Mruk, Karen; Farley, Brian M; Ritacco, Alan W et al. (2014) Calmodulation meta-analysis: predicting calmodulin binding via canonical motif clustering. J Gen Physiol 144:105-14
Malaby, Heidi L H; Kobertz, William R (2013) Molecular determinants of co- and post-translational N-glycosylation of type I transmembrane peptides. Biochem J 453:427-34
Hua, Zhengmao; Kobertz, William R (2013) Chemical derivatization and purification of peptide-toxins for probing ion channel complexes. Methods Mol Biol 995:19-30
Mruk, Karen; Shandilya, Shiven M D; Blaustein, Robert O et al. (2012) Structural insights into neuronal K+ channel-calmodulin complexes. Proc Natl Acad Sci U S A 109:13579-83

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