Hindered Diffusion of Inert Tracer Particles in the Cytoplasm of Mouse 3T3 Cells

摘要: Using fluorescence recovery after photobleaching, we have studied the diffusion of fluorescein-labeled, size-fractionated Ficoll in cytoplasmic space living Swiss 3T3 cells as a probe physical chemical properties cytoplasm. The results reported here corroborate and extend earlier experiments with dextran: nonbinding particles cytoplasm is hindered size-dependent manner. Extrapolation data suggests that larger than 260 A radius may be completely nondiffusible space. In contrast, protein solutions concentration comparable to range for not Although cannot at present distinguish among several models organization cytoplasm, these make it clear possesses some sort higher-order intermolecular interactions (structure) found simple aqueous solutions, even high concentration. These also suggest that, native whose smallest radial dimension approaches A, size important determinant diffusibility binding specificity. This would include most endosomes, polyribosomes, multienzyme complexes.