ATP and GTP Stimulate Membrane-bound but not Digitonin-solubilized -Glucan Synthases from Saprolegnia monoica

The properties and localization of Saprolegnia monoica chitin synthase differ from those of other fungi.

The presence of non-fibrillar alpha-chitin in cellulosic fungi (class Oomycetes) poses intriguing questions as to its role, subcellular localization and evolutionary significance. Previous studies reported on the similarity of chitin synthase from Saprolegnia monoica with that of other fungi. The present work describes important dissimilarities. There was no evidence that the chitin synthase of...

Subunit movements in single membrane-bound H+-ATP synthases from chloroplasts during ATP synthesis.

Subunit movements within the H(+)-ATP synthase from chloroplasts (CF(0)F(1)) are investigated during ATP synthesis. The gamma-subunit (gammaCys-322) is covalently labeled with a fluorescence donor (ATTO532). A fluorescence acceptor (adenosine 5'-(beta,gamma-imino)triphosphate (AMPPNP)-ATTO665) is noncovalently bound to a noncatalytic site at one alpha-subunit. The labeled CF(0)F(1) is integrate...

Partial Purification of Digitonin-Solubilized beta-Glucan Synthase from Red Beet Root.

An enriched glucan synthase fraction was obtained from red beet root microsomes by sequential extraction with the detergents 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate and digitonin. The digitonin suspension was centrifuged on a glycerol gradient, where a glucan synthase peak with a specific activity of 30- to 40-fold over microsomes was recovered. Most protein contaminants were ...

Co-translational targeting and translocation of the amino terminus of opsin across the endoplasmic membrane requires GTP but not ATP.

The tight coupling between ongoing translation and translocation across the mammalian endoplasmic reticulum has made it difficult to determine the requirements that are specific for translocation. We have developed an in vitro assay that faithfully mimics the co-translational targeting and translocation of the amino terminus of opsin without ongoing translation. Using this system we demonstrate...

Geranylgeranylation but Not GTP Loading