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J Cell Sci. 2014 May 1;127(Pt 9):2106-19. doi: 10.1242/jcs.141440. Epub 2014 Feb 25.

Tuning the electrical properties of the heart by differential trafficking of KATP ion channel complexes.

Author information

1
Department of Molecular Biology, Center for Biochemistry and Molecular Cell Biology, Heart Research Center Göttingen, University Medicine Göttingen, Humboldtallee 23, 37073 Göttingen, Germany.

Abstract

The copy number of membrane proteins at the cell surface is tightly regulated. Many ion channels and receptors present retrieval motifs to COPI vesicle coats and are retained in the early secretory pathway. In some cases, the interaction with COPI is prevented by binding to 14-3-3 proteins. However, the functional significance of this antagonism between COPI and 14-3-3 in terminally differentiated cells is unknown. Here, we show that ATP-sensitive K(+) (KATP) channels, which are composed of Kir6.2 and SUR1 subunits, are stalled in the Golgi complex of ventricular, but not atrial, cardiomyocytes. Upon sustained β-adrenergic stimulation, which leads to activation of protein kinase A (PKA), SUR1-containing channels reach the plasma membrane of ventricular cells. We show that PKA-dependent phosphorylation of the C-terminus of Kir6.2 decreases binding to COPI and, thereby, silences the arginine-based retrieval signal. Thus, activation of the sympathetic nervous system releases this population of KATP channels from storage in the Golgi and, hence, might facilitate the adaptive response to metabolic challenges.

KEYWORDS:

14-3-3; ATP-sensitive K+ channels; Arg-based retrieval signal; COPI; Cardiomyocyte; Coatomer; KATP; PKA; Protein kinase A; Trafficking

PMID:
24569881
PMCID:
PMC4004980
DOI:
10.1242/jcs.141440
[Indexed for MEDLINE]
Free PMC Article

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