| Elemental iron is required for a variety of normal cellular functions and vital for proper growth and development. Transferrin (Tf), a serum glycoprotein of ~80kD and synthesized in the liver, is the primary protein of inter-organ transport of nonheme iron. Tf can bind two iron atoms. Tf binds to membrane Transferrin receptors (TfRs) and taken up by endocytosis. Iron is released from Tf, within acidic endosomes, into the cytoplasm apparently through the action of DMT1. The apoTf-TfR complex is returned to the cell surface, where, apo-Tf dissociates from TfR at the extracellular pH. The classical TfR, now termed TfR1, is a homodimeric (95kD subunits) type II membrane glycoprotein that binds two molecules of Tf. Human TfR1 (human 760aa, mouse 763aa) has a cytoplasmic domain 1-67aa, 68-88aa TM, and 89-760aa as extracellular domains. A monomeric serum form or soluble TfR1 (~80kD) also exists that lacks residues 1-100aa. A second Tf receptor, TfR2, has been cloned and characterized. TfR2 shares 45% identity with TfR1, and 27% with PMSA. Human TfR2 (human alpha 801aa, Chromosome 7q22, mouse alpha 798aa) is predicted to contain a cytoplasmic domain of 1-80aa, 1 TM domain followed by 105-801aa as the extracellular domain. It is highly expressed in liver and peripheral blood mononuclear cells. In contrast to Tfr1, expression of Tfr2 is not down regulated as a result of iron overload, consistent with the absence iron-responsive element in TfR2. It is alternatively spliced to alpha and beta isoforms. TfR2-beta protein lacked the N-terminal portion of the TfR2-alpha including the putative TM domain. Applications: Suitable for use in ELISA. Western Blot, though not tested, may potentially be used as an application. Other applications not tested. Recommended Dilution: Western Blot: 1:1000-1:5000 (ECL). TfR1 (full length) is ~95kD. ELISA: 0.5-1ug/ml. Coat ELISA plates at 1ug/ml with control protein. Optimal dilutions to be determined by the researcher. Positive control: T8199-43: Transferrin Receptor 1, Human, Western Blot Positive Control (TfR1) T8199-45: Transferrin Receptor 1, Human, Soluble, Control (TfR1) Storage and Stability: May be stored at 4C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20C. Aliquots are stable for 12 months after receipt. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. |
