Transcytosis of retinol-binding protein across renal proximal tubule cells after megalin (gp 330)-mediated endocytosis
Plasma retinol-binding protein (RBP) combined with vitamin A (retinol) is partially filtered
through the glomerulus and then absorbed by proximal tubule cells, leading to recycling of
retinol to the circulation. Recently, it was shown that reabsorption of RBP-retinol complexes
by proximal tubule cells is mediated by megalin (gp 330), an apical endocytic receptor. It
was proposed that RBP is transported by megalin to lysosomes, where it is degraded, thus
liberating retinol, which then combines with newly synthesized RBP to be secreted into the …
through the glomerulus and then absorbed by proximal tubule cells, leading to recycling of
retinol to the circulation. Recently, it was shown that reabsorption of RBP-retinol complexes
by proximal tubule cells is mediated by megalin (gp 330), an apical endocytic receptor. It
was proposed that RBP is transported by megalin to lysosomes, where it is degraded, thus
liberating retinol, which then combines with newly synthesized RBP to be secreted into the …
