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, P.M., Vogel, H.J.
(2000) J.Mol.Recog. 13: 83-92
- PubMed: 10822252
- DOI: 10.1002/(SICI)1099-1352(200003/04)13:2<83::AID-JMR491>3.0.CO;2-A
- Primary Citation of Related Structures:  1DGU
- PubMed Abstract:
Calcium- 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-ba ...
Calcium- 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.
Department of Biological Sciences, University of Calgary, Alberta, Canada.