DARPP-32 in the ciliary epithelium of the eye: a neurotransmitter-regulated phosphoprotein of brain localizes to secretory cells.
DARPP-32, a phosphoprotein enriched in dopaminoceptive brain neurons containing the D-1 receptor subtype, probably functions as an intracellular third messenger to mediate some of the physiological effects of dopamine at the D-1 receptor. By immunohistochemistry in rat, cat, Rhesus monkey, and human, we have localized DARPP-32 to the non-pigmented epithelium of the ciliary body, the innermost layer of the bi-layered epithelium responsible for secretion of aqueous humor into the eye. The immunoreactive protein in rat ciliary body, identified by immunolabeling of a ciliary body extract separated by sodium dodecyl sulfate/polyacrylamide gel electrophoresis, is indistinguishable from DARPP-32 derived from rat caudatoputamen. By analogy with brain, we propose that DARPP-32 may act as a third messenger in the ciliary epithelium, probably through a dopaminergic mechanism.
D000818:Animals; D001923:Brain Chemistry; D002415:Cats; D002924:Ciliary Body / Q000032:analysis*; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D004848:Epithelium / Q000032:analysis; D005455:Fluorescent Antibody Technique; D006651:Histocytochemistry; D006801:Humans; D008253:Macaca mulatta; D009419:Nerve Tissue Proteins / Q000032:analysis* / Q000276:immunology; D018377:Neurotransmitter Agents / Q000502:physiology; D010750:Phosphoproteins / Q000032:analysis*; D051381:Rats; D011954:Receptors, Dopamine / Q000032:analysis
D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D009419:Nerve Tissue Proteins; D018377:Neurotransmitter Agents; D010750:Phosphoproteins; D011954:Receptors, Dopamine