Cubilin is a protein that in humans is encoded by the CUBNgene.[5][6][7] It is present upon the luminal surface of enterocytes of the ileum where it facilitates absorption of vitamin B12 by acting as a receptor for IF-cobalamin (intrinsic factor - vitamin B12) complexes, enabling endocytosis of complexes by means of amnionless (AMN).[8][9]
Biochemistry
Cubilinis essentially only present in the small intestine and kidneys.[10]
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^Loscalzo J, Fauci AS, Kasper DL, Hauser SL, Longo DL, Jameson JL, eds. (2022). Harrison's principles of internal medicine (21st ed.). New York: McGraw Hill. ISBN 978-1-264-26851-1.
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Bork P, Beckmann G (1993). "The CUB domain. A widespread module in developmentally regulated proteins". J. Mol. Biol. 231 (2): 539–45. doi:10.1006/jmbi.1993.1305. PMID8510165.
Aminoff M, Carter JE, Chadwick RB, et al. (1999). "Mutations in CUBN, encoding the intrinsic factor-vitamin B12 receptor, cubilin, cause hereditary megaloblastic anaemia 1". Nat. Genet. 21 (3): 309–13. doi:10.1038/6831. PMID10080186. S2CID21836060.
Kozyraki R, Fyfe J, Kristiansen M, et al. (1999). "The intrinsic factor-vitamin B12 receptor, cubilin, is a high-affinity apolipoprotein A-I receptor facilitating endocytosis of high-density lipoprotein". Nat. Med. 5 (6): 656–61. doi:10.1038/9504. PMID10371504. S2CID9392624.
Xu D, Kozyraki R, Newman TC, Fyfe JC (1999). "Genetic evidence of an accessory activity required specifically for cubilin brush-border expression and intrinsic factor-cobalamin absorption". Blood. 94 (10): 3604–6. doi:10.1182/blood.V94.10.3604.422k22_3604_3606. PMID10552972.
Kristiansen M, Aminoff M, Jacobsen C, et al. (2000). "Cubilin P1297L mutation associated with hereditary megaloblastic anemia 1 causes impaired recognition of intrinsic factor-vitamin B(12) by cubilin". Blood. 96 (2): 405–9. doi:10.1182/blood.V96.2.405. PMID10887099.
Yammani RR, Seetharam S, Seetharam B (2001). "Cubilin and megalin expression and their interaction in the rat intestine: effect of thyroidectomy". Am. J. Physiol. Endocrinol. Metab. 281 (5): E900–7. doi:10.1152/ajpendo.2001.281.5.E900. PMID11595644. S2CID1438500.