IMMUNOFLUORESCENT LOCALIZATION OF α _2u -GLOBULIN IN THE HEPATIC AND RENAL TISSUES OF RAT

Abstract

α 2u -Globulin is an androgen-inducible rat urinary protein of hepatic origin. Examination of adult male rat liver sections with rhodamine-labeled anti-α 2u -antiserum showed that the liver parenchymal cells are the site of α 2u -globulin synthesis and that all of the parenchymal cells contain this protein. Immunofluorescent localization of α 2u -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 α 2u -globulin was found to be localized only in the kidney tubules in particulate form. It is concluded that α 2u -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 α 2u reabsorption.