Human Apo-Transferrin Protein, CF

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Product Details
Citations (5)
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Human Apo-Transferrin Protein, CF Summary

Product Specifications

Endotoxin Level
<0.10 EU per 1 μg of the protein by the LAL method.
Measured in a serum-free cell proliferation assay using CHO-K1 cells.

The ED50 for this effect is <6.00 μg/mL.
Human plasma-derived Apo-Transferrin protein
The human plasma used for the isolation of this product were certified by the supplier to be negative for HIV I and II antibodies, Hepatitis C antibody and Hepatitis B antigen at the time of shipment. Human blood products should always be treated in accordance with universal handling precautions.
76-81 kDa, reducing conditions

Product Datasheets

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Carrier Free

What does CF mean?

CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our recombinant proteins. Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant protein to be stored at a more dilute concentration. The carrier free version does not contain BSA.

What formulation is right for me?

In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or as an ELISA standard. In contrast, the carrier free protein is recommended for applications, in which the presence of BSA could interfere.


Formulation Lyophilized from a 0.2 μm filtered solution in deionized water.
Reconstitution Reconstitute at 10 mg/mL in sterile, deionized water.
Shipping The product is shipped with polar packs. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage: Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
• 12 months from date of receipt at -20 to -70 °C as supplied.
• 1 month at 2-8 °C under sterile conditions after reconstitution.
• 3 months at -20 to -70 °C under sterile conditions after reconstitution.
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Background: Apo-Transferrin

Human Transferrin (Tf) is a single chain, 80 kDa member of the anion-binding superfamily of proteins (1 - 5). It is a bilobed molecule that is the product of an ancient gene duplication event (1, 6). Transferrin is synthesized as a 698 amino acid (aa) precursor that is divided into a 19 aa signal sequence plus a 679 aa mature segment that contains 19 intrachain disulfide bonds. The crystal structure of Tf reveals a protein with two flanking 340 aa globular domains. Each are composed of a beta -sheet surrounded by series of alpha -helices (1, 7). The N- and C-terminal flanking regions (or domains) will bind ferric iron through the interaction of an obligate anion (usually bicarbonate) and four amino acids (His, Asp, and two Tyr) (7, 8). Apotransferrin (or iron-free) will initially bind one atom of iron at the C-terminus, and this is followed by subsequent iron binding by the N-terminus to form holotransferrin (diferric Tf) (8, 9). Through its C-terminal iron-binding domain, holotransferrin will interact with the type I Tf receptor (TfR) on the surface of cells where it is internalized into acidified endosomes. Iron dissociates from the Tf molecule within these endosomes, and is transported into the cytosol as ferrous iron. At physiological pH, iron-free Apotransferrin is not bound by TfR. But at acidic pH, such as exists in the endosome, Apotransferrin has considerable affinity for TfR. Thus, it remains bound to TfR and is recycled back to the cell surface where a neutral pH environment dissociates ligand from receptor. Each Tf molecule recycles 100 - 150 times during its lifetime (8 - 11). In addition to TfR, transferrin is reported to bind to cubulin, IGFBP3, microbial iron-binding proteins and liver-specific TfR2 (7, 12, 13, 14). Transferrin is variably glycosylated and the degree of sialylation is suggestive of certain clinical conditions (15). Finally, Tf is highly allelic and the gene codominant, with many single aa changes noted. Three general forms are known, based on standard electrophoretic mobility. Fast Tf is known as transferrin B, slow transferrin is transferrin D, and the middle migrating transferrin is type/variant C, the most common (16, 17). Mature human TF is 73% aa identical to both mouse and rat Tf, and 68% and 71% aa identical to bovine and equine Tf, respectively.

  1. Brus, C.M. et al. (2001) Nat. Struct. Biol. 4:919.
  2. Schaeffer, E. et al. (1987) Gene 56:109.
  3. MacGillivray, R.T.A. et al. (1983) J. Biol. Chem. 258:3543.
  4. Yang, F. et al. (1984) Proc. Natl. Acad. Sci. USA 81:2752.
  5. Uzan, G. et al. (1984) Biochem. Biophys. Res. Commun. 119:273.
  6. Zak, O. et al. (2002) Biochemistry 41:7416.
  7. Gomme, P.T. and K. B. McCann (2005) Drug Discov. Today 10:267.
  8. Liu, R. et al. (2003) Biochemistry 42:12447.
  9. Pakdaman, R. et al. (1999) J. Mol. Biol. 293:1273.
  10. Hemadi, M. et al. (2004) Biochemistry 43:1736.
  11. Aisen, P. et al. (2001) Int. J. Biochem. Cell Biol. 33:940.
  12. Kozyraki, R. et al. (2001) Proc. Natl. Acad. Sci. USA 98:12941.
  13. Boulton, I.C. et al. (1998) Biochem. J. 334:269.
  14. Robb, A. and M. Wessling-Resnick (2004) Blood 104:4294.
  15. Landberg, E. et al. (1995) Biochem. Biophys. Res. Commun. 210:267.
  16. Gorg, A. et al. (1983) Hum. Genet. 64:222.
  17. Bean, P. and J.B. Peter (1994) Clin. Chem. 40:2078.
Alternate Names
ApoTransferrin; Apo-Transferrin; CD71; p90; T9; TFR; TFR1; TFRC; TR; transferrin receptor (p90, CD71); TRFR

Citations for Human Apo-Transferrin Protein, CF

R&D Systems personnel manually curate a database that contains references using R&D Systems products. The data collected includes not only links to publications in PubMed, but also provides information about sample types, species, and experimental conditions.

5 Citations: Showing 1 - 5
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  1. The VDR FokI (rs2228570) polymorphism is involved in Parkinson's disease
    Authors: C Agliardi, FR Guerini, M Zanzottera, E Bolognesi, M Meloni, G Riboldazzi, R Zangaglia, A Sturchio, C Casali, C Di Lorenzo, B Minafra, M Clerici
    Journal of the neurological sciences, 2021;428(0):117606.
    Species: Human
    Sample Types: Reference Standard
  2. Expression of Amyloidogenic Transthyretin Drives Hepatic Proteostasis Remodeling in an Induced Pluripotent Stem Cell Model of Systemic Amyloid�Disease
    Authors: RM Giadone, DC Liberti, TM Matte, JD Rosarda, C Torres-Ara, S Ghosh, JK Diedrich, S Pankow, N Skvir, JC Jean, JR Yates, AA Wilson, LH Connors, DN Kotton, RL Wiseman, GJ Murphy
    Stem Cell Reports, 2020;0(0):.
    Species: Human
    Sample Types: Whole Cells
    Applications: Bioassay
  3. DUX4 transcript knockdown with antisense 2'-O-methoxyethyl gapmers for the treatment of facioscapulohumeral muscular dystrophy
    Authors: KRQ Lim, A Bittel, R Maruyama, Y Echigoya, Q Nguyen, Y Huang, K Dzierlega, A Zhang, YW Chen, T Yokota
    Mol Ther, 2020;0(0):.
    Species: Human
    Sample Types: Whole Cells
    Applications: Bioassay
  4. Molecular Mechanisms of Membrane Curvature Sensing by a Disordered Protein
    Authors: WF Zeno, AS Thatte, L Wang, WT Snead, EM Lafer, JC Stachowiak
    J. Am. Chem. Soc., 2019;0(0):.
    Species: Human
    Sample Types: Protein
    Applications: Reference Standard
  5. Systemic combinatorial peptide selection yields a non-canonical iron-mimicry mechanism for targeting tumors in a mouse model of human glioblastoma.
    Authors: Staquicini FI, Ozawa MG, Moya CA, Driessen WH, Barbu EM, Nishimori H, Soghomonyan S, Flores LG, Liang X, Paolillo V, Alauddin MM, Basilion JP, Furnari FB, Bogler O, Lang FF, Aldape KD, Fuller GN, Höök M, Gelovani JG, Sidman RL, Cavenee WK, Pasqualini R, Arap W
    J. Clin. Invest., 2011;121(1):161-73.
    Species: Human
    Sample Types: Whole Cells
    Applications: Bioassay


  1. What are the differences between Human Holo-Transferrin Protein, CF (Catalog # 2914-HT) and Human Apo-Transferrin Protein, CF (Catalog # 3188-AT)?

    • Human Transferrin has two different iron binding domains, one at the N-terminus and one at the C-terminus. Apo-transferrin (3188-AT) is not bound to any iron atoms and Holo-Transferrin (2914-HT) has an iron atom bound at both the N- and C-terminal domains.

  2. What is the accession number associated with the Human Apo-Transferrin Protein, CF (Catalog # 3188-AT)?

    • Catalog # 3188-AT is derived from donor human plasma. It is not expressed recombinantly; therefore, no accession number is listed for this product.

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