Diffusion coefficient of membrane-associated nodes that condense to form cytokinetic contractile ring

Range ~20 nm^2/sec
Organism Fission yeast Schizosaccharomyces pombe
Reference Vavylonis D, Wu JQ, Hao S, O'Shaughnessy B, Pollard TD. Assembly mechanism of the contractile ring for cytokinesis by fission yeast. Science. 2008 Jan 4 319(5859):97-100. p.98 left column top paragraphPubMed ID18079366
Method "[Researchers] used fluorescence microscopy of live fission yeast cells to observe that membrane-bound nodes containing myosin were broadly distributed around the cell equator and assembled into a contractile ring through stochastic motions, after a meshwork of dynamic actin filaments appeared."
Comments "When first formed, nodes moved relatively little for ~10 min (Movies S5 and S6), but the mean square displacement (MSD) of the center of each node increased over time (Fig. 2E, black), consistent with 2-dimensional diffusion: MSD(t) = MSD(0) + 4Dt. The diffusion constants D distributed around 20 nm^2/s in control cells and cells treated with Latrunculin A to depolymerize actin (fig. S2). Node motions appeared uncorrelated, because the slopes of relative MSD between pairs of nodes (Fig. 2E, gray, and fig. S2B) were on average equal to the sum of the slopes of individual node MSD curves. Diffusive behavior implies that any anchors or cross-links of nodes were dynamic or very soft on minute time scales. The large mass [>22,000 kD (10)] of nodes may contribute to D being orders of magnitude smaller than D of transmembrane proteins (13)."
Entered by Uri M
ID 111109