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).

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Neurotransporters, Receptors, and Calcium Signaling Study Section (NTRC)
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Nie, Zhongzhen
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University of Massachusetts Medical School Worcester
Schools of Medicine
United States
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Kobertz, William R (2018) Oddballs in the Shaker family: Kv2-related regulatory subunits. J Gen Physiol 150:1599-1601
Bandara, H M Dhammika; Hua, Zhengmao; Zhang, Mei et al. (2017) Palladium-Mediated Synthesis of a Near-Infrared Fluorescent K+ Sensor. J Org Chem 82:8199-8205
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Kobertz, William R (2014) Stoichiometry of the cardiac IKs complex. Proc Natl Acad Sci U S A 111:5065-6
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
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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

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