Sampling the cell with anomalous diffusion - the discovery of slowness

¹ German Cancer Research Center
² German Cancer Research Center (DKFZ)

^* To whom correspondence should be addressed. E-mail: m.weiss{at}dkfz.de.

Submitted on July 9, 2007
Revised on August 22, 2007
Accepted on 30 August 2007

	Abstract

Diffusion-mediated searching for interaction partners is an ubiquitous process in cell biology. Transcription factors, for example, search specific DNA sequences, signaling proteins aim at interacting with specific co-factors, and peripheral membrane proteins try to dock to membrane domains. Brownian motion, however, is affected by molecular crowding that induces anomalous diffusion (so-called subdiffusion) of proteins and larger structures, thereby compromising diffusive transport and the associated sampling processes. Contrary to the naive expectation that subdiffusion obstructs cellular processes we show here by computer simulations that subdiffusion rather increases the probability of finding a nearby target. Consequently, important events like protein complex formation and signal propagation are enhanced as compared to normal diffusion. Hence, cells indeed benefit from their crowded internal state and the associated anomalous diffusion.

Key Words: anomalous diffusion, complex formation, diffuse-to-capture, molecular crowding, signaling, subdiffusion

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