1xo5 | pdb_00001xo5
Crystal structure of CIB1, an EF-hand, integrin and kinase-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 PubMedCIB1 (CIB) is an EF-hand-containing protein that binds multiple effector proteins, including the platelet alphaIIbbeta3 integrin and several serine/threonine kinases and potentially modulates their function. The crystal structure for Ca(2+)-bound CIB1 has been determined at 2.0 A resolution and reveals a compact alpha-helical protein containing four EF-hands, the last two of which bind calcium ions in the standard fashion seen in many other EF-hand proteins. CIB1 shares high structural similarity with calcineurin B and the neuronal calcium sensor (NCS) family of EF-hand-containing proteins. Most importantly, like calcineurin B and NCS proteins, which possess a large hydrophobic pocket necessary for ligand binding, CIB1 contains a hydrophobic pocket that has been implicated in ligand binding by previous mutational analysis. However, unlike several NCS proteins, Ca(2+)-bound CIB1 is largely monomeric whether bound to a relevant peptide ligand or ligand-free. Differences in structure, oligomeric state, and phylogeny define a new family of CIB1-related proteins that extends from arthropods to humans. Structural and biochemical characterization of CIB1 delineates a new family of EF-hand-containing proteins.,Gentry HR, Singer AU, Betts L, Yang C, Ferrara JD, Sondek J, Parise LV J Biol Chem. 2005 Mar 4;280(9):8407-15. Epub 2004 Dec 1. PMID:15574431[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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