Structural highlights
Disease[IF_HUMAN] Defects in GIF are the cause of hereditary intrinsic factor deficiency (IFD) [MIM:261000]; also known as congenital pernicious anemia. IFD is an autosomal recessive disorder characterized by megaloblastic anemia.[1] Function[IF_HUMAN] Promotes absorption of the essential vitamin cobalamin (Cbl) in the ileum. After interaction with CUBN, the GIF-cobalamin complex is internalized via receptor-mediated endocytosis. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe structure of intrinsic factor (IF) in complex with cobalamin (Cbl) was determined at 2.6-A resolution. The overall fold of the molecule is that of an alpha(6)/alpha(6) barrel. It is a two-domain protein, and the Cbl is bound at the interface of the domains in a base-on conformation. Surprisingly, two full-length molecules, each comprising an alpha- and a beta-domain and one Cbl, and two truncated molecules with only an alpha- domain are present in the same asymmetric unit. The environment around Cbl is dominated by uncharged residues, and the sixth coordinate position of Co(2+) is empty. A detailed comparison between the IF-B12 complex and another Cbl transport protein complex, trans-Cbl-B12, has been made. The pH effect on the binding of Cbl analogues in transport proteins is analyzed. A possible basis for the lack of interchangeability of human and rat IF receptors is presented. Crystal structure of human intrinsic factor: cobalamin complex at 2.6-A resolution.,Mathews FS, Gordon MM, Chen Z, Rajashankar KR, Ealick SE, Alpers DH, Sukumar N Proc Natl Acad Sci U S A. 2007 Oct 30;104(44):17311-6. Epub 2007 Oct 22. PMID:17954916[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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