Structure, binding interface and hydrophobic transitions of Ca 2+-loaded calbindin-D28K

Douglas J. Kojetin, Ronald A. Venters, David R. Kordys, Richele J. Thompson, Rajiv Kumar, John Cavanagh

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


Calbindin-D28K is a Ca2+-binding protein, performing roles as both a calcium buffer and calcium sensor. The NMR solution structure of Ca2+-loaded calbindin-D28K reveals a single, globular fold consisting of six distinct EF-hand subdomains, which coordinate Ca 2+ 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 α5 (EF3), α8 (EF4) and the EF2-EF3 and EF4-EF5 loops. Fluorescence experiments reveal that calbindin-D28K 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.

Original languageEnglish (US)
Pages (from-to)641-647
Number of pages7
JournalNature Structural and Molecular Biology
Issue number7
StatePublished - Jul 2006

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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