The F-actin side binding activity of the Arp2/3 complex is essential for actin nucleation and lamellipod extension
In: Current Biology, Jg. 11 (2001-04-01), S. 620-625
Online
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Zugriff:
Most eukaryotic cells rely on localized actin polymerization to generate and sustain the protrusion activity necessary for cell movement [1, 2]. Such protrusions are often in the form of a flat lamellipod with a leading edge composed of a dense network of actin filaments [3, 4]. The Arp2/3 complex localizes within that network in vivo [3, 4] and nucleates actin polymerization and generates a branched network of actin filaments in vitro [5–7]. The complex has thus been proposed to generate the actin network at the leading edge of crawling cells in vivo [3, 4, 8]. However, the relative contributions of nucleation and branching to protrusive force are still unknown. We prepared antibodies to the p34 subunit of the Arp2/3 complex that selectively inhibit side binding of the complex to F-actin. We demonstrate that side binding is required for efficient nucleation and branching by the Arp2/3 complex in vitro. However, microinjection of these antibodies into cells specifically inhibits lamellipod extension without affecting the EGF-stimulated appearance of free barbed ends in situ. These results indicate that while the side binding activity of the Arp2/3 complex is required for nucleation in vitro and for protrusive force in vivo, it is not required for EGF-stimulated increases in free barbed ends in vivo. This suggests that the branching activity of the Arp2/3 complex is essential for lamellipod extension, while the generation of nucleation sites for actin polymerization is not sufficient.
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The F-actin side binding activity of the Arp2/3 complex is essential for actin nucleation and lamellipod extension
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Autor/in / Beteiligte Person: | Machesky, Laura M. ; Ichetovkin, Ilia ; Condeelis, John S. ; Bailly, Maryse ; Segall, Jeffrey E. ; Grant, Wayne M. ; Zebda, Noureddine |
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Zeitschrift: | Current Biology, Jg. 11 (2001-04-01), S. 620-625 |
Veröffentlichung: | Elsevier BV, 2001 |
Medientyp: | unknown |
ISSN: | 0960-9822 (print) |
DOI: | 10.1016/s0960-9822(01)00152-x |
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