4n5x
From Proteopedia
Crystal structure of N-terminal calmodulin-like Calcium sensor of human mitochondrial ATP-Mg/Pi carrier SCaMC1
Structural highlights
FunctionSCMC1_HUMAN Calcium-dependent mitochondrial solute carrier. Mitochondrial solute carriers shuttle metabolites, nucleotides, and cofactors through the mitochondrial inner membrane. May act as a ATP-Mg/Pi exchanger that mediates the transport of Mg-ATP in exchange for phosphate, catalyzing the net uptake or efflux of adenine nucleotides into or from the mitochondria.[1] Publication Abstract from PubMedThe mitochondrial carriers play essential roles in energy metabolism. The short Ca(2+)-binding mitochondrial carrier (SCaMC) transports ATP-Mg in exchange for Pi and is important for activities that depend on adenine nucleotides. SCaMC adopts, in addition to the transmembrane domain (TMD) that transports solutes, an extramembrane N-terminal domain (NTD) that regulates solute transport in a Ca(2+)-dependent manner. Crystal structure of the Ca(2+)-bound NTD reveals a compact architecture in which the functional EF hands are sequestered by an endogenous helical segment. Nuclear magnetic resonance (NMR) relaxation rates indicated that removal of Ca(2+) from NTD results in a major conformational switch from the rigid and compact Ca(2+)-bound state to the dynamic and loose apo state. Finally, we showed using surface plasmon resonance and NMR titration experiments that free apo NTDs could specifically interact with liposome-incorporated TMD, but that Ca(2+) binding drastically weakened the interaction. Our results together provide a molecular explanation for Ca(2+)-dependent ATP-Mg flux in mitochondria. A Self-Sequestered Calmodulin-like Ca(2+) Sensor of Mitochondrial SCaMC Carrier and Its Implication to Ca(2+)-Dependent ATP-Mg/Pi Transport.,Yang Q, Bruschweiler S, Chou JJ Structure. 2014 Feb 4;22(2):209-17. doi: 10.1016/j.str.2013.10.018. Epub 2013 Dec, 12. PMID:24332718[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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