Regulation of a two-pore K+ channel by multiple subunits in Caenorhabditis elegans

K+ channels generate and tune the electrical signals that underlie the functioning of neurons and other excitable cells. We have studied a set of genetically-interacting genes, sup-9, sup-10 and unc-93, whose products are predicted to form a protein complex that when misregulated leads to severe muscle paralysis in the nematode C. elegans. We cloned sup-9 and found it encodes a K+ channel of the recently discovered mammalian two-pore family of voltage-insensitive leak channels, suggesting that SUP-10 and UNC-93, along with multiple UNC-93-like genes in Drosophila and humans, are the first regulatory subunits for two-pore K+ channels. Based on pharmacological data, we propose that gain-of-function mutations in the sup-9 channelor in its proposed subunits result in muscle paralysis through excessive K+ efflux and hyperpolarization of muscle cells. We cloned sup-18, a regulator of the channel complex, and show that SUP-18 is a type-three transmembrane protein that colocalizes with SUP-9 in muscle membranes and whose intracellular domain is similar to bacterial NADH nitroreductases that use an FMN cofactor. We identified a mutation in a predicted FMN-binding residue of SUP-18 that both eliminates its in vivo function without disrupting its membrane localization and that impairs the enzymatic activity of a related Thermophilus enzyme, suggesting that SUP-18 may couple cell metabolism with membrane excitability.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Biology.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2002

Author dc:creator

• Perez de la Cruz, Ignacio, 1973-

Advisor dc:contributor.advisor

• H. Robert Horvitz.

• Biology.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/29908

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/29908