REALISTIC MODELS OF BIOLOGICAL MOTION

The origin of biological motion can be traced back to the function of molecular motor proteins. Cytoplasmic dynein and kinesin transport org anelles within our cells moving along a polymeric filament, the microt ubule. The motion of the myosin molecules along the actin filaments is responsible for the contraction of our muscles. Recent experiments ha ve been able to reveal some important features of the motion of indivi dual motor proteins, and a new statistical physical description - ofte n referred to as ''thermal ratchets'' - has been developed for the des cription of motion of these molecules. In this approach, the motors ar e considered as Brownian particles moving along one-dimensional period ic structures due to the effect of nonequilibrium fluctuations. Assumi ng specific types of interaction between the particles the models can be made more realistic. We have been able to give analytic solutions f or our model of kinesin with elastically coupled Brownian heads and fo r the motion of the myosin filament where the motors are connected thr ough a rigid backbone. Our theoretical predictions are in a very good agreement with the various experimental results. In addition, we have considered the effects arising as a result of interaction among a larg e number of molecular motors, leading to a number of novel cooperative transport phenomena. (C) 1998 Elsevier Science B.V. All rights reserv ed.