期刊
PLOS ONE
卷 4, 期 3, 页码 -出版社
PUBLIC LIBRARY SCIENCE
DOI: 10.1371/journal.pone.0004810
关键词
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资金
- Human Frontier Science Program Organisation (HFSPO)
- The Vienna Science Research and Technology Fund (WWTF)
- The City of Vienna/Zentrum fur Innovation und Technologie
- Deutsche Forschungsgemeinschaft [FOR629]
Cells protrude by polymerizing monomeric (G) into polymeric (F) actin at the tip of the lamellipodium. Actin filaments are depolymerized towards the rear of the lamellipodium in a treadmilling process, thereby supplementing a G-actin pool for a new round of polymerization. In this scenario the concentrations of F- and G-actin are principal parameters, but have hitherto not been directly determined. By comparing fluorescence intensities of bleached and unbleached regions of lamellipodia in B16-F1 mouse melanoma cells expressing EGFP-actin, before and after extraction with Triton X-100, we show that the ratio of F- to G-actin is 3.2+/-0.9. Using electron microscopy to determine the F- actin content, this ratio translates into F- and G-actin concentrations in lamellipodia of approximately 500 mu M and 150 mu M, respectively. The excess of G-actin, at several orders of magnitude above the critical concentrations at filament ends indicates that the polymerization rate is not limited by diffusion and is tightly controlled by polymerization/ depolymerization modulators.
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