Dynamics of clathrin and adaptor proteins during endocytosis

Joshua Z. Rappoport, Shahrnaz Kemal, Alexandre Benmerah, Sanford M. Simon*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

The endocytic adaptor complex AP-2 colocalizes with the majority of clathrin-positive spots at the cell surface. However, we previously observed that AP-2 is excluded from internalizing clathrin-coated vesicles (CCVs). The present studies quantitatively demonstrate that AP-2 disengages from sites of endocytosis seconds before internalization of the nascent CCV. In contrast, epsin, an alternate adaptor for clathrin at the plasma membrane, disappeared, along with clathrin. This suggests that epsin remains an integral part of the CCV throughout endocytosis. Clathrin spots at the cell surface represent a heterogeneous population: a majority (70%) of the spots disappeared with a time course of 4 min, whereas a minority (22%) remained static for ≥30 min. The static clathrin spots undergo constant subunit exchange, suggesting that although they are static structures, these spots comprise functional clathrin molecules, rather than dead-end aggregates. These results support a model where AP-2 serves a cargo-sorting function before endocytosis, whereas alternate adaptors, such as epsin, actually link cargo to the clathrin coat surrounding nascent endocytic vesicles. These data also support a role for static clathrin, providing a nucleation site for endocytosis.

Original languageEnglish (US)
Pages (from-to)C1072-C1081
JournalAmerican Journal of Physiology - Cell Physiology
Volume291
Issue number5
DOIs
StatePublished - 2006

Keywords

  • Adaptor complex
  • Epsin
  • Total internal reflection fluorescence microscopy

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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