Roles of C-terminal region of vacuolar H+-pyrophosphatase was determined by deleted mutation

• Main Authors: Jung-Hsien Chen, 陳俊賢
• Other Authors: Rong-Long Pan
• Format: Others
• Language: en_US
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/55076731259963066077

碩士 === 國立清華大學 === 生命科學系 === 88 === Plant cell contains vacuolar H+-pyrophosphatase (EC 3.6.1.1), which catalyzes PPi hydrolysis and electrogenic translocation of proton from the cytosol to vacuole lumen. C-terminus deletion of plant V-PPase, showed different degree of decreases in specific activity and proton translocation. The expressed V-PPase of C-terminus deleted, ΔC-69 (truncate 69 amino acids about 7 kDa) particularly lose the enzymatic reaction and proton translocation, but the short fragment deleted mutantΔC-25 was remained the enzymatic ability. C-terminal deletion of V-PPase causes a release of the stimulation of enzymatic activity by KCl and inhibition by Ca2+. The truncated V-PPase longer than lost 25 amino acid lost most of K+ stimulatory and Ca2+ inhibitory effects. The C-terminus of V-PPase may contain K+ and Ca2+ binding domain. Western blot analysis and immunoflouresence microscope indicated that the C-terminal region of V-PPase is involved in protein targeting. Hence, we speculate that the C-terminus of V-PPase may play an essential role in regulating enzymatic activity and stabilizing the enzyme structure.