Immunohistochemical study of localization of gamma-glutamyl transpeptidase in the rat brain

Gamma-glutamyl transpeptidase (gamma-GTP) is a membrane-bound enzyme which is known to play a crucial role in active transport of amino acids across membrane barriers. We prepared a monoclonal antibody recognizing specifically rat gamma-GTP and investigated localization of the enzyme in the rat brain by immunohistochemistry with this antibody. The antigen was localized on the ependyma, epithelia of the choroid plexus and microvessels. More precise localization of gamma-GTP was examined with immuno-electron microscopy. The antigen was recognized on the microvilli and cilia of the ependymal cells, microvilli of the choroid epithelial cells and luminal membranes of the vascular endothelial cells.