VGL K Kv3-Shaw: Vertebrate K+ channels related to Drosophila shaw (Kvα subunits encoded by gene subfamily Kv3)

Abstract

This chapter describes the structure and function of voltage-gated (VLG) potassium channels that are related to Drosophila Shaw—Kvα subunits encoded by gene subfamily Kv3. The vertebrate K+ channel subunits whose primary amino acid sequences are most closely related to those of Drosophila Shaw are grouped in the voltage-gated K+ channel subfamily 3. The vertebrate Shaw-related channel mRNAs undergo extensive alternate splicing events within their protein-coding regions. The linear organization, regulatory mechanisms, and splicing patterns of the four independent—Kv3.1 to Kv3.4—subfamily genes appear broadly similar, consistent with an evolutionary origin at some time involving duplication of an ancestral gene. Alignment of the vertebrate Shaw-related channels shows high conservation of the hydrophobic core regions. Thus putative Kv3.1:Kv3.4 heteromultimers display fast-inactivating currents that are several-fold larger than those seen in oocytes injected with the same amount of Kv3.4 cRNA alone. This pattern appears to hold for Kv3.l:Kv3.4 heteromultimers and channels that are obtained following injection with Kv3.4 and Kv3.2 or Kv3.3 cRNAs. Evidence for C-terminal subcellular targeting domains in alternatively spliced products of the Kv3.2 gene is also elaborated in the chapter.