Fibronectin receptor internalization and AP-2 complex reorganization in potassium-depleted fibroblasts

Georgi Altankov, Frederick Grinnell

Research output: Contribution to journalArticle

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Abstract

Potassium-depleted fibroblasts are unable to develop polarized morphology and lack coated pits. Experiments were carried out to measure internalization of fibronectin receptors (FNR) in potassium-depleted cells and possible association of FNR with AP-2 complexes after adding potassium back to the cells, which restores cell polarization. AP-2 complexes are the cell surface component of coated pits that contain both clathrin and membrane receptor binding domains. Potassium-depleted fibroblasts endocytosed antibody-tagged FNR and also internalized fluorescent fibronectin that previously had been adsorbed to the substratum. During cell polarization, antibody-tagged FNR reorganized into fibrillar structures along stress fibers beginning from nucleation sites at cell margins. Plasma membrane AP-2 complexes, which were undetectable in potassium-depleted cells, reappeared at the cell surface above the nucleus and then spread toward the cell margins. The results show that endocytosis of FNR can occur at least partially by a coated pit-independent mechanism.

Original languageEnglish (US)
Pages (from-to)299-309
Number of pages11
JournalExperimental Cell Research
Volume216
Issue number2
DOIs
StatePublished - Feb 1995

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ASJC Scopus subject areas

  • Cell Biology

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