1dgu | pdb_00001dgu
HOMOLOGY-BASED MODEL OF CALCIUM-SATURATED CIB (CALCIUM-AND INTEGRIN-BINDING PROTEIN)
Structural highlights
Function[CIB1_HUMAN] May convert the inactive conformation of integrin alpha-IIb/beta3 to an active form through binding to the integrin cytoplasmic domain. Induces cell migration and spreading mediated through integrin (possibly via focal adhesion complexes). Functions as a negative regulator of stress activated MAP kinase (MAPK) signaling pathways. May play a role in regulation of apoptosis. Interacts with and up-regulates PTK2/FAK1 activity. Down regulates inositol 1,4,5-trisphosphate receptor-dependent calcium signaling. Participates in endomitotic cell cycle, a form of mitosis in which both karyokinesis and cytokinesis are interrupted and is a hallmark of megakaryocyte differentiation.[1] [2] [3] [4] [5] [6] 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 PubMedCalcium- and integrin-binding protein (CIB) binds to the 20-residue alphaIIb cytoplasmic domain of platelet alphaIIbbeta3 integrin. Amino acid sequence similarities with calmodulin (CaM) and calcineurin B (CnB) allowed the construction of homology-based models of calcium-saturated CIB as well as apo-CIB. In addition, the solution structure of the alphaIIb cytoplasmic domain in 45% aqueous trifluoroethanol was solved by conventional two-dimensional NMR methods. The models indicate that the N-terminal domain of CIB possesses a number of positively charged residues in its binding site that could interact with the acidic carboxy-terminal LEEDDEEGE sequence of alphaIIb. The C-terminal domain of CIB seems well-suited to bind the sequence WKVGFFKR, which forms a well-structured alpha helix; this is analogous to calmodulin and calcineurin B, which also bind alpha helices. Similarities between the C-terminal domains of CIB and calmodulin suggest that binding of CIB to the cytoplasmic domain of alphaIIb may be affected by fluctuations in the intracellular calcium concentration. Structures of the platelet calcium- and integrin-binding protein and the alphaIIb-integrin cytoplasmic domain suggest a mechanism for calcium-regulated recognition; homology modelling and NMR studies.,Hwang PM, Vogel HJ J Mol Recognit. 2000 Mar-Apr;13(2):83-92. PMID:10822252[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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