Referenced in: none

Automatically associated channels: Kv1.5

Title: SAP97 increases Kv1.5 currents through an indirect N-terminal mechanism.

Authors: Jodene Eldstrom, Woo Sung Choi, David F Steele, David Fedida

Journal, date & volume: FEBS Lett., 2003 Jul 17 , 547, 205-11

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/12860415

Abstract
The functional interaction of the voltage-gated potassium channel hKv1.5 with the PDZ domain containing protein SAP97 has been investigated. In marked contrast with the known dependence of SAP97-induced Kv1 potassium current down-regulation on the channel C-termini, SAP97 increased hKv1.5 current through an indirect interaction with the Kv1.5 N-terminus. Deletion of the Kv1.5 N-terminus eliminated the SAP97-mediated increase in potassium currents whereas deletion of the channel's C-terminal PDZ binding motif had no effect. In contrast with other Kv1-SAP97 interactions, no physical interaction could be detected in vivo or in vitro between the two proteins. The proteins did not co-localize in cardiac myocytes nor did they co-immunoprecipitate from transfected HEK cells. Yeast two-hybrid experiments also failed to detect any interaction between the two proteins, but in one experiment of six, Kv1.5 co-immunoprecipitated very inefficiently with SAP97 from rat ventricular myocytes. Thus, we conclude that the influence of SAP97 on Kv1.5 potassium current levels is dependent upon a novel regulatory mechanism.