Mechanism and size cutoff for steric exclusion from actin-rich cytoplasmic domains

Lee W. Janson, Keith Ragsdale, Katherine Luby-Phelps

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Abstract

Subdomains of the cytoplasmic volume in tissue culture cells exclude large tracer particles relative to small. Evidence suggests that exclusion of the large particles is due to molecular sieving by the dense meshwork of microfilaments found in these compartments, but exclusion as a result of the close apposition of the dorsal and ventral plasma membrane of the cell in these regions has not been ruled out conclusively. In principle, these two mechanisms can be distinguished by the dependence of exclusion on tracer particle size. By fluorescence ratio imaging we have measured the partition coefficient (P/P(o)) into excluding compartments for tracer particles ranging in radius from 1 to 41 nm. The decay of P/P(o) as a function of particle radius is better fitted by three molecular sieving models than by a slit pore model. The sieving models predict a percolation cutoff radius of the order of 50 nm for partitioning into excluding compartments.

Original languageEnglish (US)
Pages (from-to)1228-1234
Number of pages7
JournalBiophysical Journal
Volume71
Issue number3
StatePublished - Sep 1996

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Molecular Models
Optical Imaging
Plasma Cells
Actin Cytoskeleton
Particle Size
Actins
Cell Culture Techniques
Cell Membrane

ASJC Scopus subject areas

  • Biophysics

Cite this

Mechanism and size cutoff for steric exclusion from actin-rich cytoplasmic domains. / Janson, Lee W.; Ragsdale, Keith; Luby-Phelps, Katherine.

In: Biophysical Journal, Vol. 71, No. 3, 09.1996, p. 1228-1234.

Research output: Contribution to journalArticle

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