2L4H

The Solution Structure of Calcium Bound CIB1

Summary for 2L4H

• Entry DOI: 10.2210/pdb2l4h/pdb
• Related: 1XO5 1Y1A 2L4I
• NMR Information: BMRB: 17329
• Descriptor: Calcium and integrin-binding protein 1, CALCIUM ION (2 entities in total)
• Functional Keywords: calcium and integrin binding protein 1, metal binding protein
• Biological source: Homo sapiens (human)
• Cellular location: Membrane; Lipid-anchor: Q99828
• Total number of polymer chains: 1
• Total formula weight: 24587.42

Authors

Huang, H.,Vogel, H.J. (deposition date: 2010-10-06, release date: 2011-03-09, Last modification date: 2024-05-01)

Primary citation

Huang, H.,Ishida, H.,Yamniuk, A.P.,Vogel, H.J.
Solution Structures of Ca2+-CIB1 and Mg2+-CIB1 and Their Interactions with the Platelet Integrin {alpha}IIb Cytoplasmic Domain.
J.Biol.Chem., 286:17181-17192, 2011

PubMed Abstract: The calcium- and integrin-binding protein 1 (CIB1) is a ubiquitous Ca(2+)-binding protein and a specific binding partner for the platelet integrin αIIb cytoplasmic domain, which confers the key role of CIB1 in hemostasis. CIB1 is also known to be involved in apoptosis, embryogenesis, and the DNA damage response. In this study, the solution structures of both Ca(2+)-CIB1 and Mg(2+)-CIB1 were determined using solution-state NMR spectroscopy. The methyl groups of Ile, Leu, and Val were selectively protonated to compensate for the loss of protons due to deuteration. The solution structure of Ca(2+)-CIB1 possesses smaller opened EF-hands in its C-domain compared with available crystal structures. Ca(2+)-CIB1 and Mg(2+)-CIB1 have similar structures, but the N-lobe of Mg(2+)-CIB1 is slightly more opened than that of Ca(2+)-CIB1. Additional NMR experiments, such as chemical shift perturbation and methyl group solvent accessibility as measured by a nitroxide surface probe, were carried out to further characterize the structures of Ca(2+)-CIB1 and Mg(2+)-CIB1 as well as their interactions with the integrin αIIb cytoplasmic domain. NMR measurements of backbone amide proton slow motion (microsecond to millisecond) dynamics confirmed that the C-terminal helix of Ca(2+)-CIB1 is displaced upon αIIb binding. The EF-hand III of both Ca(2+)-CIB1 and Mg(2+)-CIB1 was identified to be directly involved in the interaction of CIB1 with αIIb. Together, these data illustrate that CIB1 behaves quite differently from related EF-hand regulatory calcium-binding proteins, such as calmodulin or neuronal calcium sensor proteins.

PubMed: 21388953
DOI: 10.1074/jbc.M110.179028

Experimental method

SOLUTION NMR