A direct proof from the analysis of urinary protein—cationic charge preferential reabsorption in renal proximal tubules—

Abstract

There are two possible pathways of reabsorbing filtered proteins in the renal tubular cells. One is receptor mediated system and the other is cationic charge preferential interaction between cationic protein molecules and the polyanionic tubular brush border. Recently, the receptor mediated reabsorption systems have been clarified such as multi-ligand receptor “Megalin-Cubilin complex” and neonatal Fcγ receptor. However, cationic charge preferential interaction needs to be proven. The brush border of the renal proximal tubules has a polyanionic charge. Since IgG molecules have a wide range of charge diversity, reabsorption of urinary IgG molecules are supposed to be influenced by the electrostatic interaction. We investigated the cationic charge preferential interaction system by analyzing the charge diversities of serum and urinary IgG. Here, I will show our results to prove the cationic charge preferential reabsorption in renal proximal tubules and illustrate the mechanisms of tubular protein reabsorption.