Rab3a interacting molecule (RIM) and the tethering of presynaptic transmitter release site-associated Cav2.2 calcium channels

Abstract

Event Abstract Back to Event Rab3a interacting molecule (RIM) and the tethering of presynaptic transmitter release site-associated Cav2.2 calcium channels Fiona K. Wong1* and Elise F. Stanley1 1 Toronto Western Research Institute, Laboratory of Synaptic Transmission, Genes and Development, Canada Current studies suggest that presynaptic Cav2.2 calcium channels are attached to the transmitter release site within the active zone by a molecular tether. ‘Rab3a Interacting Molecule’ (RIM) is known to play a role in synaptic vesicle docking but has recently been proposed (Kiyonaka et al. Nature Neurosci. 2007) to also fulfill the channel tethering role. However, this suggestion is at variance with results published in our earlier study (Khanna et al., Neurosci. 2006). The main difference in these studies was that we failed to demonstrate co-immunoprecipitation (co-IP) of RIM and CaV2.2 whereas this was observed in the later study. Objective: Three hypotheses were explored to account for the different conclusions between Kiyonaka et al and Khanna et al reports, respectively: 1) the use of different anti-RIM antibodies, mRIM and pRIM, 2) the stringency of the lysate solubilization buffer: digitonin or RIPA and, 3) the type of brain fraction used to generate the lysate: brain microsomes or purified synaptosome membrane. Materials and Methods: Immunoprecipitation (IP) and Western blotting of avian brain lysates. Results: We could not distinguish between the two studies based on antibody selectivity or solubilization buffers. While IP of Cav2.2 (Ab571) from whole brain lysate did co-IP RIM, the two proteins failed to co-IP from purified brain synaptosome membrane lysate using anti-CaV2.2 or either anti-RIM antibody. We also ruled out occlusion of the Ab571 binding site (CaV2.2 II-III loop) as two antibodies against a very different region of the channel (distal C terminal) also failed to co-IP RIM. Conclusions: While our findings are consistent with the existence of a Cav2.2/RIM protein complex in brain we conclude that this complex is not significant at presynaptic terminals. Thus, it is highly unlikely that RIM serves as a key scaffold protein for active zone Cav2.2 calcium channels. Conference: B.R.A.I.N. platform in Physiology poster day 2009, Toronto, ON, Canada, 16 Dec - 16 Dec, 2009. Presentation Type: Poster Presentation Topic: Poster presentations Citation: Wong FK and Stanley EF (2009). Rab3a interacting molecule (RIM) and the tethering of presynaptic transmitter release site-associated Cav2.2 calcium channels. Front. Neurosci. Conference Abstract: B.R.A.I.N. platform in Physiology poster day 2009. doi: 10.3389/conf.neuro.03.2009.17.050 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 18 Dec 2009; Published Online: 18 Dec 2009. * Correspondence: Fiona K Wong, Toronto Western Research Institute, Laboratory of Synaptic Transmission, Genes and Development, Toronto, Canada, fwong@uhnres.utoronto.ca Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Fiona K Wong Elise F Stanley Google Fiona K Wong Elise F Stanley Google Scholar Fiona K Wong Elise F Stanley PubMed Fiona K Wong Elise F Stanley Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.