Nature Research, Nature Neuroscience, 11(8), p. 1503-1509, 2005
DOI: 10.1038/nn1557
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We report the first example of a K+ channel beta-subunit that is also a serine/threonine kinase. MPS-1 is a single-transmembrane domain protein that coassembles with voltage-gated K+ channel KVS-1 in the nervous system of the nematode Caenorhabditis elegans. Biochemical analysis shows that MPS-1 can phosphorylate KVS-1 and other substrates. Electrophysiological analysis in Chinese hamster ovary (CHO) cells demonstrates that MPS-1 activity leads to a significant decrease in the macroscopic current. Single-channel analysis and biotinylation assays indicate that MPS-1 reduces the macroscopic current by lowering the open probability of the channel. These data are consistent with a model that predicts that the MPS-1-dependent phosphorylation of KVS-1 sustains cell excitability by controlling K+ flux.