Structure, binding interface and hydrophobic transitions of Ca(2+)-loaded calbindin-D(28K).
Kojetin, D.J., Venters, R.A., Kordys, D.R., Thompson, R.J., Kumar, R., Cavanagh, J.(2006) Nat Struct Mol Biol 13: 641-647
- PubMed: 16799559
- DOI: https://doi.org/10.1038/nsmb1112
- Primary Citation of Related Structures:
2F33, 2G9B - PubMed Abstract:
Calbindin-D(28K) is a Ca2+-binding protein, performing roles as both a calcium buffer and calcium sensor. The NMR solution structure of Ca2+-loaded calbindin-D(28K) reveals a single, globular fold consisting of six distinct EF-hand subdomains, which coordinate Ca2+ in loops on EF1, EF3, EF4 and EF5. Target peptides from Ran-binding protein M and myo-inositol monophosphatase, along with a new target from procaspase-3, are shown to interact with the protein on a surface comprised of alpha5 (EF3), alpha8 (EF4) and the EF2-EF3 and EF4-EF5 loops. Fluorescence experiments reveal that calbindin-D(28K) adopts discrete hydrophobic states as it binds Ca2+. The structure, binding interface and hydrophobic characteristics of Ca2+-loaded calbindin-D(28K) provide the first detailed insights into how this essential protein may function. This structure is one of the largest high-resolution NMR structures and the largest monomeric EF-hand protein to be solved to date.
Organizational Affiliation:
Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695, USA.