IMMUNE-LOCALIZATION OF THE CALCITRIOL RECEPTOR, CALBINDIN-D-28K AND THE PLASMA-MEMBRANE CALCIUM-PUMP IN THE HUMAN EYE

Using immunohistochemical methods, we detected epitopes of the calcitr iol receptor, the ATP-dependent plasma membrane calcium pump and the 2 8kD vitamin D-dependent calcium-binding protein in sections of the hum an eye. In retinal photoreceptors, vitamin D receptor, plasma membrane calcium pump and calcium-binding protein epitopes were detected in th e outer nuclear layer. Epitopes for the vitamin D receptor and the cal cium-binding protein were present in the inner and outer segments of t he photoreceptors, where visual transduction occurs. All three protein s were detected in some cells of the ganglion cell layer, the inner nu clear layer, and the retinal pigment epithelium. Epitopes for these pr oteins also were noted in the ciliary body epithelium. VDR epitopes we re seen in lens epithelium. Some immunostaining for VDR, PMCA and calb indin-D-28k also was present in the endothelium and in the basal epith elium of the cornea. The presence of these proteins in several tissues of the human eye suggests that the proteins may play a role in the ce llular physiology of the eye. Their exact functions in the eye remain undetermined.