Messages diffuse faster than messengers

• Autores: Pando, Bernardo; Ponce Dawson, Silvina Martha; Mak, Don-On Daniel; Pearson, John E.
• Año de publicación: 2006
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: BINDING; EFFECTIVE DIFFUSION; FLUORESCENCE RECOVERY AFTER PHOTOBLEACHING; TAGGED PARTICLES; TRAPS
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

In many cell-signaling pathways, information is transmitted by the diffusion of messenger molecules. Diffusion coefficients characterize the messenger's spatial range and the characteristic times of signal propagation. Inside cells, particles usually diffuse in the presence of immobile binding sites (or traps). It is well known that binding to traps results in an effective diffusion coefficient that is smaller than the free coefficient in media free of traps. To measure effective diffusion coefficients in cells, "tagged" particles are often used. Radioactive calcium was used in a giant squid axon and in cytosolic extracts of Xenopus laevis oocytes. Fluorescence recovery after photobleaching yields diffusion coefficients from observations of the distribution of fluorescently labeled proteins. In the absence of traps, free diffusion coefficients give both the rate at which single-particle mean square displacements increase and the rate at which information in the form of inhomogeneities in particle concentration spread out with time. We show here that, in the presence of traps, information diffuses faster than single particles. Thus, messages diffuse faster than messengers. Tagged-particle experiments give the single-particle diffusion coefficients and, thus, can underestimate the rate of diffusive signal propagation. © 2006 by The National Academy of Sciences of the USA.
Fil: Pando, Bernardo. Massachusetts Institute of Technology; Estados Unidos
Fil: Ponce Dawson, Silvina Martha. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina
Fil: Mak, Don-On Daniel. University of Pennsylvania; Estados Unidos
Fil: Pearson, John E.. Los Alamos National Laboratory;