Abstract
α2u-Globulin is an androgen-inducible rat urinary protein of hepatic origin. Examination of adult male rat liver sections with rhodamine-labeled anti-α2u-antiserum showed that the liver parenchymal cells are the site of α2u-globulin synthesis and that all of the parenchymal cells contain this protein. Immunofluorescent localization of α2u-globulin in male kidney sections revealed the existence of the protein in the cells of proximal convoluted tubules, in the loop of Henle as well as in the distal convoluted tubule. The collecting ducts did not bind the fluorescent labeled antibody. Intraperitoneally administered rhodamine-labeled α2u-globulin was found to be localized only in the kidney tubules in particulate form. It is concluded that α2u-globulin after its synthesis and release from the hepatic parenchymal cells is filtered into the renal tubular lumen and that both kinds of convoluted tubules as well as the loop of Henle are actively involved in α2u reabsorption.