2rpw
From Proteopedia
Structure of a peptide derived from H+-V-ATPase subunit a
Structural highlights
FunctionVPP1_YEAST Subunit of the V0 complex of vacuolar(H+)-ATPase (V-ATPase), a multisubunit enzyme composed of a peripheral complex (V1) that hydrolyzes ATP and a membrane integral complex (V0) that translocates protons (PubMed:11278748, PubMed:1491220, PubMed:8798414). V-ATPase is responsible for acidifying and maintaining the pH of intracellular compartments (PubMed:11278748, PubMed:1491220). Is present only in vacuolar V-ATPase complexes; enzymes containing this subunit have a 4-fold higher ratio of proton transport to ATP hydrolysis than complexes containing the Golgi/endosomal isoform and undergo reversible dissociation of V1 and V0 in response to glucose depletion (PubMed:11278748, PubMed:8798414).[1] [2] [3] Publication Abstract from PubMedThe 3D structure of a peptide derived from the putative transmembrane segment 7 (TM7) of subunit a from H(+)-V-ATPase from Saccharomyces cerevisiae has been determined by solution state NMR in SDS. A stable helix is formed from L736 up to and including Q745, the lumenal half of the putative TM7. The helical region extends well beyond A738, as was previously suggested based on NMR studies of a similar peptide in DMSO. The pKa of both histidine residues that are important for proton transport was measured in water and in SDS. The differences that are found demonstrate that the histidine residues interact with the SDS polar heads. In detergent, circular dichroism data indicate that the secondary structure of the peptide depends on the pH and the type of detergent used. Using solid-state NMR, it is shown that the peptide is immobile in phospholipid bilayers, which means that it is probably not a single transmembrane helix in these samples. The environment is important for the structure of TM7, so in subunit a it is probably held in place by the other transmembrane helices of this subunit. Structural properties of a peptide derived from H+ -V-ATPase subunit a.,Vermeer LS, Reat V, Hemminga MA, Milon A Biochim Biophys Acta. 2009 May;1788(5):1204-12. Epub 2009 Feb 26. PMID:19249284[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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