Referenced in: none

Automatically associated channels: Kv1.4 , Kv3.1 , Kv4.2 , Kv4.3

Title: Developmental expression of NCS-1 (frequenin), a regulator of Kv4 K+ channels, in mouse heart.

Authors: Tomoe Y Nakamura, Eron Sturm, David J Pountney, Barbara Orenzoff, Michael Artman, William A Coetzee

Journal, date & volume: Pediatr. Res., 2003 Apr , 53, 554-7

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/12612193

Abstract
The channel proteins responsible for the cardiac transient outward K+ current (Ito) of human and rodent heart are composed, in part, of pore-forming Kv4.3 or Kv4.2 principal subunits. Recent reports implicate K+ channel interacting proteins (members of the neuronal Ca2+-binding protein family) as subunits of the Ito channel complex. We reported that another Ca2+-binding protein, frequenin [or neuronal calcium center protein-1 (NCS-1)], also functions as a Kv4 auxiliary subunit in the brain. By examining cardiac expression of NCS-1, the aim of this study was to examine the potential physiologic relevance of this protein as an additional regulator of cardiac Ito. Immunoblot analysis demonstrates NCS-1 protein to be expressed in adult mouse ventricle at levels comparable to that found in some brain regions. Cardiac NCS-1 protein expression levels are much higher in fetal and neonatal mouse hearts when compared with the adult. Immunocytochemical analysis of isolated neonatal mouse ventricular myocytes demonstrates co-localization of NCS-1 and Kv4.2 proteins at the sarcolemma. Given its high levels of expression in the heart, NCS-1 should be considered an important potential Kv4 regulatory subunit, particularly in the immature heart.