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Weiss N, Hameed S, Fernández-Fernández JM, Fablet K, Karmazinova M, Poillot C, Proft J, Chen L, Bidaud I, Monteil A, Huc-Brandt S, Lacinova L, Lory P, Zamponi GW, De Waard M
A Ca(v)3.2/syntaxin-1A signaling complex controls T-type channel activity and low-threshold exocytosis.
J. Biol. Chem.. 2012 Jan;287(4):2810-8, PMID: 22130660
T-type calcium channels represent a key pathway for Ca(2+) entry near the resting membrane potential. Increasing evidence supports a unique role of these channels in fast and low-threshold exocytosis in an action potential-independent manner, but the underlying molecular mechanisms have remained unknown. Here, we report the existence of a syntaxin-1A/Ca(v)3.2 T-type calcium channel signaling complex that relies on molecular determinants that are distinct from the synaptic protein interaction site (synprint) found in synaptic high voltage-activated calcium channels. This interaction potently modulated Ca(v)3.2 channel activity, by reducing channel availability. Other members of the T-type calcium channel family were also regulated by syntaxin-1A, but to a smaller extent. Overexpression of Ca(v)3.2 channels in MPC 9/3L-AH chromaffin cells induced low-threshold secretion that could be prevented by uncoupling the channels from syntaxin-1A. Altogether, our findings provide compelling evidence for the existence of a syntaxin-1A/T-type Ca(2+) channel signaling complex and provide new insights into the molecular mechanism by which these channels control low-threshold exocytosis.
BIOCHEMISTRY & MOLECULAR BIOLOGY
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