Active zone protein CAST is a component of conventional and ribbon synapses in mouse retina.
CAST is a novel cytomatrix at the active zone (CAZ)-associated protein. In conventional brain synapses, CAST forms a large molecular complex with other CAZ proteins, including RIM, Munc13-1, Bassoon, and Piccolo. Here we investigated the distribution of CAST and its structurally related protein, ELKS, in mouse retina. Immunofluorescence analyses revealed that CAST and ELKS showed punctate signals in the outer and inner plexiform layers of the retina that were well-colocalized with those of Bassoon and RIM. Both proteins were found presynaptically at glutamatergic ribbon synapses, and at conventional GABAergic and glycinergic synapses. Moreover, immunoelectron microscopy revealed that CAST, like Bassoon and RIM, localized at the base of synaptic ribbons, whereas ELKS localized around the ribbons. Both proteins also localized in the vicinity of the presynaptic plasma membrane of conventional synapses in the retina. These results indicated that CAST and ELKS were novel components of the presynaptic apparatus of mouse retina.
KAN Research Institute, Kyoto 600-8815, Japan.
Maki
M
Deguchi-Tawarada
Eiji
E
Inoue
Etsuko
E
Takao-Rikitsu
Marie
M
Inoue
Isao
I
Kitajima
Toshihisa
T
Ohtsuka
Yoshimi
Y
Takai
D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D051379:Mice; D016253:Microscopy, Immunoelectron; D009419:Nerve Tissue Proteins / Q000378:metabolism; D012160:Retina / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D013569:Synapses / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D020691:rab GTP-Binding Proteins
D018528:ATP-Binding Cassette Transporters; C512841:Abca4 protein, mouse; C498441:Bsn protein, mouse; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; C486769:Erc1 protein, mouse; C505599:Erc2 protein, mouse; D009419:Nerve Tissue Proteins; D020691:rab GTP-Binding Proteins