Abstract
We present a model for the packing of clathrin molecules into the characteristic hexagons and pentagons covering coated pits and vesicles. The assembly unit is a symmetrical trimer with three extended legs. Polymerization of these units occurs in seconds under suitable conditions, giving empty polyhedral cages resembling the structures around coated vesicles. Images of small, negatively stained fragments of cages, assembled directly on electron microscope grids, reveal details of the structure, which correlate well with the predicted features of the model. There is one clathrin trimer at each polyhedral vertex, and each leg of the trimer extends along two neighboring polyhedral edges. Quasi-equivalent packing in pentagons and hexagons in polyhedra of different sizes requires a variable joint at the vertex of the molecule and a hinge in each leg. The construction of clathrin coats is remarkable for the extended fibrous contacts that each molecule makes with many others. Such contacts may confer mechanical strength combined with flexibility needed when a vesicle is pinched off from the membrane.
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Selected References
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- Bretscher M. S., Thomson J. N., Pearse B. M. Coated pits act as molecular filters. Proc Natl Acad Sci U S A. 1980 Jul;77(7):4156–4159. doi: 10.1073/pnas.77.7.4156. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Crowther R. A., Amos L. A. Harmonic analysis of electron microscope images with rotational symmetry. J Mol Biol. 1971 Aug 28;60(1):123–130. doi: 10.1016/0022-2836(71)90452-9. [DOI] [PubMed] [Google Scholar]
- Crowther R. A., Finch J. T., Pearse B. M. On the structure of coated vesicles. J Mol Biol. 1976 Jun 5;103(4):785–798. doi: 10.1016/0022-2836(76)90209-6. [DOI] [PubMed] [Google Scholar]
- Harrison S. C. Virus crystallography comes of age. Nature. 1980 Aug 7;286(5773):558–559. doi: 10.1038/286558a0. [DOI] [PubMed] [Google Scholar]
- Heuser J. Three-dimensional visualization of coated vesicle formation in fibroblasts. J Cell Biol. 1980 Mar;84(3):560–583. doi: 10.1083/jcb.84.3.560. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kanaseki T., Kadota K. The "vesicle in a basket". A morphological study of the coated vesicle isolated from the nerve endings of the guinea pig brain, with special reference to the mechanism of membrane movements. J Cell Biol. 1969 Jul;42(1):202–220. doi: 10.1083/jcb.42.1.202. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Keen J. H., Willingham M. C., Pastan I. H. Clathrin-coated vesicles: isolation, dissociation and factor-dependent reassociation of clathrin baskets. Cell. 1979 Feb;16(2):303–312. doi: 10.1016/0092-8674(79)90007-2. [DOI] [PubMed] [Google Scholar]
- Kirchhausen T., Harrison S. C. Protein organization in clathrin trimers. Cell. 1981 Mar;23(3):755–761. doi: 10.1016/0092-8674(81)90439-6. [DOI] [PubMed] [Google Scholar]
- Laemmli U. K. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. doi: 10.1038/227680a0. [DOI] [PubMed] [Google Scholar]
- Nandi P. K., Pretorius H. T., Lippoldt R. E., Johnson M. L., Edelhoch H. Molecular properties of the reassembled coat protein of coated vesicles. Biochemistry. 1980 Dec 9;19(25):5917–5921. doi: 10.1021/bi00566a039. [DOI] [PubMed] [Google Scholar]
- OOSAWA F., KASAI M. A theory of linear and helical aggregations of macromolecules. J Mol Biol. 1962 Jan;4:10–21. doi: 10.1016/s0022-2836(62)80112-0. [DOI] [PubMed] [Google Scholar]
- Pearse B. M. Clathrin: a unique protein associated with intracellular transfer of membrane by coated vesicles. Proc Natl Acad Sci U S A. 1976 Apr;73(4):1255–1259. doi: 10.1073/pnas.73.4.1255. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pearse B. M. Coated vesicles from pig brain: purification and biochemical characterization. J Mol Biol. 1975 Sep 5;97(1):93–98. doi: 10.1016/s0022-2836(75)80024-6. [DOI] [PubMed] [Google Scholar]
- Pearse B. M. On the structural and functional components of coated vesicles. J Mol Biol. 1978 Dec 25;126(4):803–812. doi: 10.1016/0022-2836(78)90021-9. [DOI] [PubMed] [Google Scholar]
- Schook W., Puszkin S., Bloom W., Ores C., Kochwa S. Mechanochemical properties of brain clathrin: interactions with actin and alpha-actinin and polymerization into basketlike structures or filaments. Proc Natl Acad Sci U S A. 1979 Jan;76(1):116–120. doi: 10.1073/pnas.76.1.116. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ungewickell E., Branton D. Assembly units of clathrin coats. Nature. 1981 Jan 29;289(5796):420–422. doi: 10.1038/289420a0. [DOI] [PubMed] [Google Scholar]
- Unwin P. N., Henderson R. Molecular structure determination by electron microscopy of unstained crystalline specimens. J Mol Biol. 1975 May 25;94(3):425–440. doi: 10.1016/0022-2836(75)90212-0. [DOI] [PubMed] [Google Scholar]
- Williams R. C., Fisher H. W. Electron microscopy of tobacco mosaic virus under conditions of minimal beam exposure. J Mol Biol. 1970 Aug 28;52(1):121–123. doi: 10.1016/0022-2836(70)90181-6. [DOI] [PubMed] [Google Scholar]
- Woodward M. P., Roth T. F. Coated vesicles: characterization, selective dissociation, and reassembly. Proc Natl Acad Sci U S A. 1978 Sep;75(9):4394–4398. doi: 10.1073/pnas.75.9.4394. [DOI] [PMC free article] [PubMed] [Google Scholar]