Signal transduction versus buffering activity in Ca(2+)-binding proteins.
The three-dimensional structure of calbindin D9k in the absence of Ca2+ has been determined using NMR spectroscopy in solution, allowing the first direct analysis of the consequences of Ca2+ binding for a member of the calmodulin superfamily of proteins. The overall response in calbindin D9k is much attenuated relative to the current model for calmodulin and troponin C. These results demonstrate a novel mechanism for modulating the conformational response to Ca(2+)-binding in calmodulin superfamily proteins and provide insights into how their Ca(2+)-binding domains can be fine-tuned to remain essentially intact or respond strongly to ion binding, in relation to their functional requirements.
Skelton
N J
NJ
Department of Molecular Biology, Scripps Research Institute, La Jolla, California 92037, USA.
Kördel
J
J
Akke
M
M
Forsén
S
S
Chazin
W J
WJ
D000818:Animals; D001059:Apoproteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D002021:Buffers; D064026:Calbindins; D002118:Calcium / Q000378:metabolism; D002417:Cattle; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D011485:Protein Binding; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D064030:S100 Calcium Binding Protein G / Q000737:chemistry* / Q000378:metabolism; D015398:Signal Transduction; D014336:Troponin / Q000737:chemistry; D019209:Troponin C
D001059:Apoproteins; D002021:Buffers; D064026:Calbindins; D011994:Recombinant Proteins; D064030:S100 Calcium Binding Protein G; D014336:Troponin; D019209:Troponin C; D002118:Calcium