Nephritogenic glycoprotein. IX. Plasma Zn-alpha2-glycoprotein as a second source of nephritogenic glycoprotein in urine.

Glomerular basement membrane (GBM) damage has been considered as the only source of the nephritogenic glycoprotein excreted in urine. However, in the course of our investigation on the glycoprotein or glycopeptide isolated from the urine of a disease group seldom affected with GBM damage, it appeared that a second source of the nephritogenic glycoprotein excreted in the urine is in blood plasma; that is, in Zn-alpha2-glycoprotein. Zn-alpha2-glycoprotein is the only plasma protein which has a common determinant with nephritogenic urinary glycoprotein or glycopeptides. It was proposed that plasma Zn-alpha2-glycoprotein may play the role of a carrier protein of the nephritogenic renal glycoprotein.