Under construction: building the macromolecular superstructure and signaling components of an electrical synapse.
A great deal is now known about the protein components of tight junctions and adherens junctions, as well as how these are assembled. Less is known about the molecular framework of gap junctions, but these also have membrane specializations and are subject to regulation of their assembly and turnover. Thus, it is reasonable to consider that these three types of junctions may share macromolecular commonalities. Indeed, the tight junction scaffolding protein zonula occluden-1 (ZO-1) is also present at adherens and gap junctions, including neuronal gap junctions. On the basis of these earlier observations, we more recently found that two additional proteins, AF6 and MUPP1, known to be associated with ZO-1 at tight and adherens junctions, are also components of neuronal gap junctions in rodent brain and directly interact with connexin36 (Cx36) that forms these junctions. Here, we show by immunofluorescence labeling that the cytoskeletal-associated protein cingulin, commonly found at tight junctions, is also localized at neuronal gap junctions throughout the central nervous system. In consideration of known functions related to ZO-1, AF6, MUPP1, and cingulin, our results provide a context in which to examine functional relationships between these proteins at Cx36-containing electrical synapses in brain--specifically, how they may contribute to regulation of transmission at these synapses, and how they may govern gap junction channel assembly and/or disassembly.
Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3E 0J9, Canada.
B D
BD
Lynn
Xinbo
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Li
J I
JI
Nagy
D000818:Animals; D001921:Brain / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D017630:Connexins / Q000378:metabolism; D054351:Electrical Synapses / Q000378:metabolism*; D017629:Gap Junctions / Q000378:metabolism*; D007150:Immunohistochemistry; D016547:Kinesins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D046912:Multiprotein Complexes / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D062826:Zonula Occludens-1 Protein / Q000378:metabolism; D000097004:Gap Junction delta-2 Protein
D002352:Carrier Proteins; D017630:Connexins; D016547:Kinesins; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D009218:Myosins; D062826:Zonula Occludens-1 Protein; D000097004:Gap Junction delta-2 Protein; C490657:Afdn protein, mouse; C489227:Cgn protein, mouse; C491750:Mpdz protein, mouse; C569043:Tjp1 protein, mouse