The roles of cubilin and megalin, two multiligand receptors, in proximal tubule function: possible implication in the progression of renal disease.

Proteins that have not been retained by the glomerulus are reabsorbed in the proximal tubule by endocytosis, a process that involves binding at the apical pole of the tubule cell, vesicular internalization and subsequent lysosomal degradation. Data presented in this review indicate that the initial recognition step involves two high molecular weight proteins, megalin and cubilin, which have multiligand properties and can therefore account for the wide variety of proteins reabsorbed. Given the potential importance of transepithelial protein traffic in the induction of interstitial fibrosis, the identification of these receptors may have implications in the progression of acute or chronic renal disease and may provide a target for therapeutic intervention.