Association of Intracellular Low-density Vesicles with Plasma Membranes from Saccharomyces cerevisiae NCYC 366
| Autor: | Paul A. Henschke, D. Susan Thomas, Anthony H. Rose, Felicity J. Veazey |
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| Rok vydání: | 1983 |
| Předmět: | |
| Zdroj: | Microbiology. 129:2927-2938 |
| ISSN: | 1465-2080 1350-0872 |
| DOI: | 10.1099/00221287-129-9-2927 |
| Popis: | Summary: Fractionation on sucrose density gradients of spheroplast lysates from Saccharomyces cerevisiae NCYC 366 yielded a fraction with a peak density of 1.05 g ml−1, intermediate between that of membranes and intracellular low-density vesicles. Electron microscopy showed the fraction to consist of membranes associated with intracellular vesicles. Evidence for the presence of plasma membranes in the association fraction was obtained by using 125I-labelled spheroplasts. The fraction was free from detectable amounts of cytochromes and DNA. Fractionation on sucrose density gradients of incubation mixtures containing isolated crude plasma-membranes and vesicles gave rise to a visible intermediate-density band, which electron microscopy showed to contain membranes associated with vesicles. Evidence for the presence of plasma membranes in the in vitro intermediate-density band came from incubating mixtures containing 125I-labelled crude plasma-membranes, and evidence for the presence of vesicles came from using 125I-labelled vesicles. Supplementing incubation mixtures with calcium chloride sharply increased the size of the intermediate-density band. Cycloheximide and methylbenzimidazol-2-yl-carbamate had no effect on its formation. Purified plasma-membranes failed to form an intermediate-density band when incubated with vesicles. Supplementing these incubation mixtures with calcium chloride did not produce an intermediate-density band, but caused extensive association of vesicles with plasma membranes that pelleted in gradients. Isolated vesicles were not osmotically active; their polyphosphate content was 1.61 μmol orthophosphate equivalent (mg vesicle protein)−1. They had diameters in the range 0.45-0.65 μm, as measured on electron micrographs of thin sections. The data reported provide further evidence for a role for intracellular low-density vesicles in envelope growth in S. cerevisiae. |
| Databáze: | OpenAIRE |
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