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Åke Lernmark

Principal investigator

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Preparation and characterization of plasma membrane-enriched fractions from rat pancreatic islets

Author

  • ÅKe Lernmark
  • Anne Nathans
  • Donald F. Steiner

Summary, in English

Methods have been developed for the isolation on a semi-micro scale of a plasma membrane-enriched fraction from rat islets of Langerhans. An important feature of these experiments is the use of 125I-labeled wheat germ agglutinin as a specific probe for plasma membrane-containing fractions. The partly purified plasma membrane fraction had a density in sucrose of about 1.10 and was enriched in the activities of 5′-nucleotidase, alkaline phosphatase, sodium-potassium, and magnesium- dependent ATPases and adenylate cyclase. It contained only very low levels of acid phosphatase, cytochrome c oxidase, insulin, and RNA. Further purification was hampered by the relatively small amounts of fresh plasma membrane material that could be obtained from 16-24 rats in each experiment. When islets were prelabeled with radioactive fucose, the plasma membrane-enriched fraction contained radioactivity at a four- to fivefold higher specific activity than the whole islet homogenate. Sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis of plasma membrane-enriched fractions pooled from several experiments revealed a distinctive pattern of protein bands as compared with other less pure fractions. With respect to rapidity, apparent specificity, and easy reversibility of the labeling of the plasma membrane fraction, 125I-wheat germ agglutinin provides a highly useful tool for the detection of microgram quantities of plasma membrane components which should be applicable to many other systems as well.

Publishing year

1976-11-01

Language

English

Pages

606-623

Publication/Series

Journal of Cell Biology

Volume

71

Issue

2

Document type

Journal article

Publisher

Rockefeller University Press

Status

Published

ISBN/ISSN/Other

  • ISSN: 0021-9525