Function of a novel calcium-binding protein, visinin.

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We reported in 1985 that visinin is 24kDa and a cone specific protein. We have isolated visinin cDNA and characterized the encoded protein. We also examined the effect of visinin and anti-visinin serum on guanylate cyclase activity from frog rod outer segments.1. Visinin cDNA was isolated from chick retinal lambdagtll cDNA library, using anti-visinin serum. The nucleotide sequence revealed that visinin has three E-F hand structure and is a calcium binding protein. Visinin protein expressed in E. Coli exhibited Ca binding activity.2. Western blot and immunohistochemistry using an epitope-selected visinin antibody demonstrated that visinin exist only in the retinal cone and pinealocytes in chick.3. Visinin isolated from E. coli in which visinin was expressed and anti-visinin serum did not affect the activity of guanylate cyclase from frog r6d outer segments.4. The amounts of visinin in the pineal organ culture induced 4-8 folds in the light, but not in the dark.5. These data suggest that visinin may be involved in phototransduction in the retinal cone cell and pinealocytes through calcium metabolism.