Three-dimensional visualization of coated vesicle formation in fibroblasts - PubMed (original) (raw)

Three-dimensional visualization of coated vesicle formation in fibroblasts

J Heuser. J Cell Biol. 1980 Mar.

Abstract

Fibroblasts apparently ingest low density lipoproteins (LDL) by a selective mechanism of receptor-mediated endocytosis involving the formation of coated vesicles from the plasma membrane. However, it is not known exactly how coated vesicles collect LDL receptors and pinch off from the plasma membrane. In this report, the quick-freeze, deep-etch, rotary-replication method has been applied to fibroblasts; it displays with unusual clarity the coats that appear under the plasma membrane at the start of receptor-mediated endocytosis. These coats appear to be polygonal networks of 7-nm strands or struts arranged into 30-nm polygons, most of which are hexagons but some of which are 5- and 7-sided rings. The proportion of pentagons in each network increases as the coated area of the plasma membrane puckers up from its planar configuration (where the network is mostly hexagons) to its most sharply curved condition as a pinched-off coated vesicle. Coats around the smallest vesicles (which are icosahedrons of hexagons and pentagons) appear only slightly different from "empty coats" purified from homogenized brain, which are less symmetrical baskets containing more pentagons than hexagons. A search for structural intermediates in this coat transformation allows a test of T. Kanaseki and K. Kadota's (1969. J. Cell Biol. 42:202--220.) original idea that an internal rearrangement in this basketwork from hexagons to pentagons could "power" coated vesicle formation. The most noteworthy variations in the typical hexagonal honeycomb are focal juxtapositions of 5- and 7-sided polygons at points of partial contraction and curvature in the basketwork. These appear to precede complete contraction into individual pentagons completely surrounded by hexagons, which is the pattern that characterizes the final spherical baskets around coated vesicles.

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References

    1. J Cell Biol. 1966 Feb;28(2):209-32 - PubMed
    1. J Ultrastruct Res. 1966 Sep;16(1):1-12 - PubMed
    1. J Cell Biol. 1967 Nov;35(2):357-76 - PubMed
    1. J Ultrastruct Res. 1968 Jan;22(1):63-89 - PubMed
    1. J Cell Biol. 1969 Jul;42(1):202-20 - PubMed

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