title: The immediately releasable pool of mouse chromaffin cell vesicles is coupled to P/Q-type calcium channels via the synaptic protein interaction site.
abstract: It is generally accepted that the immediately releasable pool is a group of readily releasable vesicles that are closely associated with voltage dependent Ca(2+) channels. We have previously shown that exocytosis of this pool is specifically coupled to P/Q Ca(2+) current. Accordingly, in the present work we found that the Ca(2+) current flowing through P/Q-type Ca(2+) channels is 8 times more effective at inducing exocytosis in response to short stimuli than the current carried by L-type channels. To investigate the mechanism that underlies the coupling between the immediately releasable pool and P/Q-type channels we transiently expressed in mouse chromaffin cells peptides corresponding to the synaptic protein interaction site of Cav2.2 to competitively uncouple P/Q-type channels from the secretory vesicle release complex. This treatment reduced the efficiency of Ca(2+) current to induce exocytosis to similar values as direct inhibition of P/Q-type channels via ω-agatoxin-IVA. In addition, the same treatment markedly reduced immediately releasable pool exocytosis, but did not affect the exocytosis provoked by sustained electric or high K(+) stimulation. Together, our results indicate that the synaptic protein interaction site is a crucial factor for the establishment of the functional coupling between immediately releasable pool vesicles and P/Q-type Ca(2+) channels.
authors: Laboratorio de Fisiología y Biología Molecular, Instituto de Fisiología, Biología Molecular y Neurociencias (CONICET), Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors: Yanina D
authors: YD
authors: Álvarez
authors: Ana Verónica
authors: AV
authors: Belingheri
authors: Andrés E
authors: AE
authors: Perez Bay
authors: Scott E
authors: SE
authors: Javis
authors: H William
authors: HW
authors: Tedford
authors: Gerald
authors: G
authors: Zamponi
authors: Fernando D
authors: FD
authors: Marengo
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D020865:Calcium Channels, P-Type / Q000378:metabolism*; D020907:Calcium Channels, Q-Type / Q000378:metabolism*; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000378:metabolism*; D005089:Exocytosis / Q000502:physiology; D051379:Mice; D022142:Secretory Vesicles / Q000378:metabolism*
chemical_list: D020865:Calcium Channels, P-Type; D020907:Calcium Channels, Q-Type; D002118:Calcium
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