Squid photoreceptor terminals synthesize calexcitin, a learning related protein.
Nerve endings of squid photoreceptor neurons generate large synaptosomes upon homogenization of the optic lobe. Using several independent methods, these presynaptic structures have been shown to synthesize a wealth of soluble, cytoskeletal and nuclear encoded mitochondrial proteins, and to account for essentially all the translation activity of the synaptosomal fraction. We are now presenting evidence that calexcitin, a learning related, Ca(2+)-binding protein of the B photoreceptors of Hermissenda crassicornis (a mollusk), is synthesized and subjected to post-translational modifications in the squid photoreceptor terminals. In view of the essential role of presynaptic protein synthesis in long-term memory formation in Aplysia, our data suggest that a comparable role may be played by calexcitin synthesized in the squid photoreceptor terminals.
Eyman
Maria
M
Dipartimento di Fisiologia Generale e Ambientale, Università di Napoli "Federico II", Via Mezzocannone 8, 80134, Naples, Italy.
Crispino
Marianna
M
Kaplan
Barry B
BB
Giuditta
Antonio
A
D000818:Animals; D015153:Blotting, Western; D029742:Caenorhabditis elegans Proteins; D002135:Calcium-Binding Proteins / Q000096:biosynthesis*; D049832:Decapodiformes; D019204:GTP-Binding Proteins / Q000096:biosynthesis*; D007858:Learning; D009411:Nerve Endings / Q000378:metabolism*; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism* / Q000648:ultrastructure
D029742:Caenorhabditis elegans Proteins; D002135:Calcium-Binding Proteins; D019204:GTP-Binding Proteins; C102751:cex-2 protein, C elegans