1990 Fiscal Year Final Research Report Summary
Mechanism of Ion Transport by H^+-ATPase and H^+/K^+-ATPase
| Project/Area Number |
01480528
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
代謝生物化学
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| Research Institution | Osaka University |
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Principal Investigator |
FUTAI Masamitsu Osaka University ISIR Professor, 産業科学研究所 (50012646)
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| Co-Investigator(Kenkyū-buntansha) |
MORIYAMA Yoshinori Osaka University ISIR Research Assistant, 産業科学研究所, 助手 (10150658)
SHIMOMURA Shoji Ministry of Agriculture, Forestry and Fisheries NIAR Chief of laboratory of plan, 農業生物資源研究所, 室長 (90116046)
MAEDA Masatomo Osaka University ISIR Associate Professor, 産業科学研究所, 助教授 (80190297)
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| Project Period (FY) |
1989 – 1990
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| Keywords | H^+-ATPase / H^+ / K^+-ATPase / Synaptic vesicles / ATP / H^+ transport / Gastric acid secretion |
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| Research Abstract |
The H^+ -ATPase translocates H^+ coupling with hydrolysis of ATP. We studied three type ATPases : H^+ -ATPase (ATP synthase) of Escherichia coli plasma membrane (similar to mitochondrial enzyme) ; H^+ -ATPase of synaptic vesicles or neurosecretory gastric parietal cells responsible for acid secretion into stomach. Major results obtained are summarized as follows. 1. Glycine rich sequence (Gly-Gly-Ala-Gly-Val-Gly-Lys-Thr, residues 149 - 156) of E. Coli H^+ -ATPase was found to be near the gamma phosphate moiety of ATP, and important for catalysis. Especially Thr-156 is essential for catalysis. 2. The carboxyl terminal moiety of the gamma subunit of E. Coli H^+ -ATPase was found to be essential for coupling between ATP hydrolysis and H^+ -translocation. 3. We found that about 20 % of the membrane protein in synaptic vesicles was H^+ -ATPase, and this ATPase forms electrochemical gradient of H^+ essential for transport of neurotransmitters. 4. We obtained the cDNA and gene for gastric H^+/K^+ -ATPase from rat and human, and found this gene was transcribed only in gastric parietal cells. Furthermore we found two gastric specific nucleotide sequence motifs and proteins specifically bound to the motifs. Chemical modification studies also showed important residues in the catalytic site of H^+/K^+ -ATPase. Comparative studies on H^+ translocating ATPases have been useful for understanding complicated vectorial enzymes.
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