Referenced in: none

Automatically associated channels: Cav2.2

Title: The immediately releasable pool of mouse chromaffin cell vesicles is coupled to P/Q-type calcium channels via the synaptic protein interaction site.

Authors: Yanina D Alvarez, Ana Verónica Belingheri, Andrés E Perez Bay, Scott E Javis, H William Tedford, Gerald Zamponi, Fernando D Marengo

Journal, date & volume: PLoS ONE, 2013 , 8, e54846

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/23382986

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.