Developmental Expression of NCS-1 (Frequenin), a Regulator of Kv4 K+Channels, in Mouse Heart
作者:
TOMOE NAKAMURA,
ERON STURM,
DAVID POUNTNEY,
BARBARA ORENZOFF,
MICHAEL ARTMAN,
WILLIAM COETZEE,
期刊:
Pediatric Research
(OVID Available online 2003)
卷期:
Volume 53,
issue 4
页码: 554-557
ISSN:0031-3998
年代: 2003
出版商: OVID
数据来源: OVID
摘要:
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 Itochannel 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.
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