Transmitter release face Ca2+ channel clusters persist at isolated presynaptic terminals.
Ca(2+) influx through N-type Ca(2+) channels (CaV2.2) is known to be critical for transmitter release at many synapses. These channels are known to be localized to transmitter release sites, but their anchoring mechanism remains unknown. Recent studies have demonstrated that presynaptic organization is subject to interactions with the postsynaptic cell or the intervening extracellular matrix. We used a previously described high-affinity antibody against the N-type Ca(2+) channels, Ab571, to localize Ca(2+) channel clusters at the release face of an isolated giant calyx-type synapse to test whether the maintenance of these clusters requires an intact extracellular matrix or contact with the postsynaptic cell. Because the number of Ca(2+) channel clusters was unchanged after extracellular matrix dispersal or nerve terminal isolation, we conclude that presynaptic transmitter release face Ca(2+) clusters can be maintained independently of extracellular influences. Our results suggest that a presynaptic molecular scaffold is responsible for the maintenance of release site Ca(2+) channel clusters.
Cellular and Molecular Biology Division, Toronto Western Research Institute, UHN Toronto, Ontario, Canada.
Li
L
Sun
Qi
Q
Li
Rajesh
R
Khanna
Allen W
AW
Chan
Fiona
F
Wong
Elise F
EF
Stanley
D000818:Animals; D020864:Calcium Channels, N-Type / Q000378:metabolism*; D002642:Chick Embryo; D005109:Extracellular Matrix / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism; D017729:Presynaptic Terminals / Q000502:physiology / Q000648:ultrastructure
D020864:Calcium Channels, N-Type; D005353:Fibronectins; D008562:Membrane Glycoproteins; D018377:Neurotransmitter Agents; C029967:nidogen