HORMONE, GROWTH-FACTOR, AND VITAMIN HANDLING BY PROXIMAL TUBULE CELLS

The proximal tubule in the kidney is a main organ for the metabolic cl earance of small peptide hormones, and is intensively involved in reab sorption, storage and homeostatic regulation of different vitamins. Re cently, the endocytic membrane protein megalin has been shown to bind several smaller peptides, including insulin and epidermal growth facto r, as well as to bind and mediate uptake of transcobalamin-B-12, attra cting new attention on the cellular mechanisms involved in these proce sses.