title: Localization of gamma glutamyl transpeptidase in bovine retina.
abstract: Gamma-glutamyl transpeptidase (GGTP) is a membrane bound enzyme which has an important role in regulation of glutathione and glutamate in the retina. We have used histochemical and colorimetric enzyme assays to localize GGTP in the bovine retina and choroid. Our results demonstrate that (i) GGTP is present in retinal microvessels but not choroidal microvessels. (ii) Retinal microvascular endothelium loses the ability to express GGTP in cultured cells. (iii) GGTP is present in Muller cells. (iv) Isolated and purified rod outer segments contain high levels of GGTP. (v) Retinal pigment epithelial cells (RPE) in vivo and in culture contain GGTP. The findings of this study lend support to the concept that GGTP may be a biochemical marker for cellular systems which are part of specialized diffusion barriers.
authors.affiliation: Retina Research Laboratory, Jules Stein Eye Institute, UCLA School of Medicine 90024-1771.
authors.forename: L S
authors.initials: LS
authors.lastname: Morse
authors.forename: K
authors.initials: K
authors.lastname: Steinsapir
authors.forename: J
authors.initials: J
authors.lastname: Terrell
authors.forename: Y
authors.initials: Y
authors.lastname: Sidikaro
mesh_terms: D000818:Animals; D002151:Calorimetry; D002196:Capillaries / Q000032:analysis / Q000201:enzymology; D002417:Cattle; D002478:Cells, Cultured; D002829:Choroid / Q000032:analysis / Q000098:blood supply / Q000201:enzymology; D004730:Endothelium, Vascular / Q000032:analysis / Q000201:enzymology; D006651:Histocytochemistry; D007124:Immunoenzyme Techniques; D010857:Pigment Epithelium of Eye / Q000032:analysis / Q000201:enzymology; D012160:Retina / Q000032:analysis / Q000201:enzymology*; D012171:Retinal Vessels / Q000032:analysis / Q000201:enzymology; D012374:Rod Cell Outer Segment / Q000032:analysis / Q000201:enzymology; D005723:gamma-Glutamyltransferase / Q000032:analysis*
chemical_list: D005723:gamma-Glutamyltransferase