Membrane contents of distinct subpopulations of coated vesicles determined by scanning transmission electron microscopy

Clifford J. Steer, Margaret E. Bisher, Benes L. Trus, James F. Hainfeld, Joseph S. Wall, Alasdair C. Steven

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7 Scopus citations


In order to investigate the heterogeneity of clathrin-coated vesiscle purified from rat liver, and to quantitate rigorously their membrane contents, we have analyzed scanning transmission electron micrographs of unstained coated vesicles before and after extraction with the non-ionic detergent Triton X-100, as well as of vesicles whose coats had been removed by dialysis against 10mM or 100 mM Tis (pH 8.2). Their respective distributions of particle masses were thus determined and compared, in light of complementary biochemical quantitations of lipid and protein. Smaller coated particles, 25-45 MDa in mass and 60-80 nm in diameter, lose no mass when extracted with Triton, and disappear when their coats are dissociated. We conclude that they do not contain membrane vesicles, although they have dense, presumably proteinaceous, cores, They may represent particles generated during tissue homogenization or, possibly, a storage form of clathrin. The remaining 70% contain bona fide vesicles: these particles are 75-150 nm in diameter, and their average mass is about 80 MDa, of which 48 MDa is contributed by coat proteins, 10-12 MDa by phospholipid and cholesterol, and 20-22 MDa by vesicle-associated proteins. Their vesicles are of two types: smaller, denser, vesicles that contain substantial amounts of internalized material, and larger, less dense, vesicles that do niot. The distinction between them may, in view of other finding, reflect a difference between coated vesicles derived respectively from the Golgi and the plasma membrane.

Original languageEnglish (US)
Pages (from-to)167-180
Number of pages14
JournalBBA - Biomembranes
Issue number2
StatePublished - Feb 18 1988

Bibliographical note

Funding Information:
We thank Ms. Kristin Elmore for assistance with specimen preparation for STEM, Mr. Frank Kito for electron microscopy, and Ms. Avis Hutchings for preparing the manuscript. The Brookhaven STEM is supported by NIH Biotechnology Resource Grant R-01777. J.S.W. is supported by the Office of Health and Environmental Research of the Department of Energy.


  • Clathrin
  • Coated vesicle
  • Molecular weight determination
  • Receptor-mediated endocytosis
  • Scanning transmission electron microscopy


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