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Ca^2+^ and Mg^2+^/ATP Independently Trigger Homotypic Membrane Fusion in Gastric Secretory Membranes by Joseph G. Duman; Gaurav Singh; Ga Yi Lee; Terry E. Machen; John G. Forte is a Biochemistry, Genetics and Molecular Biology article available to read on EtoBox.

What is Ca^2+^ and Mg^2+^/ATP Independently Trigger Homotypic Membrane Fusion in Gastric Secretory Membranes about?

Exocytic activation of gastric parietal cells represents a massive transformation. We studied a step in this process, homotypic fusion of H,K-ATPase-containing tubulovesicles, using R18 dequenching. Ca(2+) and Mg(2+)/ATP each caused dramatic dequenching, reflecting a change in R18 distribution from 5% to 65-90% of the assay's membranes in 2.5 min. These stimuli also triggered fusion between tubulovesicles and liposomes. Independent confirmation that dequenching represented membrane fusion was established by separating tubulovesicle-liposome fusion products on density gradients. Only agents that trigger fusion allowed the transmembrane H,K-ATPase to move to low-density fractions along with R18. EC(50) for Ca(2+)-triggered fusion was 150 nm and for Mg(2+)/ATP-triggered fusion 1 mm, the latter having a Hill coefficient of 2.5. ATP-triggered fusion was specific for Mg(2+)/ATP, required ATP hydrolysis, and was insensitive to inhibition of NSF and/or H,K-ATPase. Fusion initiated by either trigger caused tubulovesicles to become resistant to subsequent challenge by either trigger. Ca(2+) and Mg(2+)/ATP-triggered fusion required protein component(s) in tubulovesicles, though this was requi

Who reads Ca^2+^ and Mg^2+^/ATP Independently Trigger Homotypic Membrane Fusion in Gastric Secretory Membranes?

Author

Joseph G. Duman; Gaurav Singh; Ga Yi Lee; Terry E. Machen; John G. Forte

Publisher

John Wiley and Sons; Wiley (Blackwell Publishing); Blackwell Publishing Inc.; Wiley (ISSN 1398-9219)

Published

2002

Language

EN

Field

Biochemistry, Genetics and Molecular Biology (Life Sciences)