Transport of retinol from the blood to the retina: an autoradiographic study of the pigment epithelial cell surface receptor for plasma retinol-binding protein

Abstract

Weanling rats were injected with 125I-labeled retinol binding protein and their ocular tissues were examined by light and electron microscope autoradiography at 10 min and 1 hr after injection. Combined with earlier work on isolated cells, the results show that receptors for retinol binding protein are present on the basal and lateral plasma membrane of retinal pigment epithelial cells. The pigment epithelium of the pars plana and ciliary body also contain plasma membrane receptors for retinol binding protein. In appears as though the entire plasma membrane of the ciliary pigment epithelium contains receptors for the binding protein.