Sw. Chouinard et al., Evidence for voltage-gated potassium channel beta-subunits with oxidoreductase motifs in human and rodent pancreatic beta cells, RECEPT CHAN, 7(3), 2000, pp. 237-243
Voltage-gated K+ channel alpha subunits (K(V)alpha) have been previously id
entified in pancreatic islet beta -cells where it has been suggested they h
ave a role in membrane repolarization and insulin secretion. Here we report
the cloning of the three mammalian KVP subunits, including splice variants
of these subunits. from both human and rat pancreatic islets and from the
rat insulinoma cell Line INS-1. Two of the splice variants, K(V)beta 1a and
K(V)beta3, previously reported to be neuronal tissue specific, are express
ed in islets and INS-1 cells. In addition, a splice variant of K(v)beta2 th
at lacks two potential protein kinase C phosphorylation sites at the amino
terminus is present. Immunoblot analysis suggests a high level of K(V)beta2
subunit protein in rat pancreatic islets and immunoprecipitation with anti
-K(V)beta2 antibody pulls down a protein from INS-1 cells that reacts with
anti-aldose reductase antibody. The KVP subunits, which are attached to the
cytoplasmic face of the a subunits and are members of the aldose reductase
superfamily of NADPH oxidoreductases, may have an as yet undetermined role
in the regulation of insulin secretion by the intracellular redox potentia
l. Finally, we suggest that a systematic nomenclature for KVP subunits firs
t proposed by McCormack et al. be adopted for this family of potassium chan
nel subunits as it corresponds with the nomenclature used for their cognate
K(V)alpha subunits.