– Transferrins are iron binding transport proteins which can bind two Fe(3+) ions in association with the binding of an anion, usually bicarbonate. It is responsible for the transport of iron from sites of absorption and heme degradation to those of storage and utilization. Serum transferrin may also have a further role in stimulating cell proliferation. Transferrin Protein, Rat, Recombinant (His & KSI) is expressed in E. coli expression system with N-6xHis-KSI tag. The predicted molecular weight is 89.9 kDa and the accession number is P12346.