Two microsomal-associated iron-binding proteins observed in rat small intestinal cells during iron absorption

Acrylamide gel electrophoresis of microsomal protein obtained from rat small intestinal mucosal cells, after an injection of ³H]leucine, demonstrated increased quantities of two soluble iron-binding proteins during iron absorption, one with a high molecular weight (about 400 000) and the other of intermediate molecular weight (80 000). Both proteins were present in a ribosomal-enriched sub-fraction obtained during purification of the microsomal membrame but were not identified among the purified membrane proteins.