A Novel β Subunit Increases Rate of Inactivation of Specific Voltage-gated Potassium Channel α Subunits

• Published in: The Journal of biological chemistry 1995-03, Vol.270 (11), p.6272
• Main Authors: Michael J. Morales, Robert C. Castellino, Anne L. Crews, Randall L. Rasmusson, Harold C. Strauss
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.11.6272

Voltage-gated potassium channel β subunits are cytoplasmic proteins that co-purify with the pore-forming α subunits. One of these subunits, Kvβ1 from rat brain, was previously demonstrated to increase the rate of inactivation of Kv1.1 and Kv1.4 when co-expressed in Xenopus oocytes. We have cloned and characterized a novel voltage-gated K + channel β subunit. The cDNA, designated Kvβ3, has a 408-amino acid open reading frame. It possesses a unique 79-amino acid N-terminal leader, but is identical with rat Kvβ1 over the 329 C-terminal amino acids. The Kvβ3 transcript was found in many tissues, but was most abundant in aorta and left ventricle of the heart. Co-expression of Kvβ3 with K + channel α subunits shows that this β subunit can increase the rate of inactivation from 4- to 7-fold in a Kv1.4 or Shaker B channel. Kvβ3 had no effect on Kv1.1, unlike Kvβ1 which can increase rate of inactivation of this α subunit more than 100-fold. Other kinetic parameters were unaffected. This study shows that voltage-gated K + channel β subunits are present outside the central nervous system, and that at least one member of this family selectively modulates inactivation of K + channel α subunits.