2bbc | pdb_00002bbc

Structure of Cobalamin-complexed Bovine Transcobalamin in trigonal crystal form

spinqualitylabelsall models 2bbc, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2bbc is a 1 chain structure with sequence from Bovin. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: B12, CL Related: 2bb5, 2bb6 Gene: TCN2, TC2 (BOVIN) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [TCO2_BOVIN] Primary vitamin B12-binding and transport protein. Delivers cobalamin to cells. 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 PubMed Cobalamin (Cbl, vitamin B(12)) serves for two essential cofactors in mammals. The pathway for its intestinal absorption, plasma transport, and cellular uptake uses cell surface receptors and three Cbl-transporting proteins, haptocorrin, intrinsic factor, and transcobalamin (TC). We present the structure determination of a member of the mammalian Cbl-transporter family. The crystal structures of recombinant human and bovine holo-TCs reveal a two-domain architecture, with an N-terminal alpha(6)-alpha(6) barrel and a smaller C-terminal domain. One Cbl molecule in base-on conformation is buried inside the domain interface. Structural data combined with previous binding assays indicate a domain motion in the first step of Cbl binding. In a second step, the weakly coordinated ligand H(2)O at the upper axial side of added H(2)O-Cbl is displaced by a histidine residue of the alpha(6)-alpha(6) barrel. Analysis of amino acid conservation on TC's surface in orthologous proteins suggests the location of the TC-receptor-recognition site in an extended region on the alpha(6)-alpha(6) barrel. The TC structure allows for the mapping of sites of amino acid variation due to polymorphisms of the human TC gene. Structural information is used to predict the overall fold of haptocorrin and intrinsic factor and permits a rational approach to the design of new Cbl-based bioconjugates for diagnostic or therapeutic drug delivery. Structural basis for mammalian vitamin B12 transport by transcobalamin.,Wuerges J, Garau G, Geremia S, Fedosov SN, Petersen TE, Randaccio L Proc Natl Acad Sci U S A. 2006 Mar 21;103(12):4386-91. Epub 2006 Mar 14. PMID:16537422 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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