The structure of the macrophage actin skeleton.

H. L. Yin, J. H. Hartwig

Research output: Contribution to journalReview article

29 Scopus citations

Abstract

The actin skeleton of the macrophage consists of a three-dimensional network of actin filaments and associated proteins. The organization of this multiprotein structure is regulated at several levels in cells. Receptor stimulation induces a massive actin polymerization at the cell cortex, changes in cell shape and active cellular movements. Gelsolin may have a pivotal role in restructuring the actin skeleton in response to agonist stimulation, as the activity of this potent actin-modulating protein is regulated by both Ca2+ and polyphosphoinositides. Micromolar concentrations of Ca2+ activate gelsolin to bind to the sides of actin filaments, sever, and cap the filament end. Polyphosphoinositides, in particular PIP and PIP2, release gelsolin from the filament ends. A structure-function analysis of gelsolin indicates that its N-terminal half is primarily responsible for severing actin filaments, and elucidates mechanisms by which Ca2+ and phospholipid may regulate gelsolin functions. The ultrastructure of actin filaments in the macrophage cortical cytoplasm is regulated, to a large extent, by the actin cross-linking protein, actin-binding protein (ABP) which defines filament orthogonality.

Original languageEnglish (US)
Pages (from-to)169-184
Number of pages16
JournalJournal of cell science. Supplement
Volume9
StatePublished - 1988

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