Biophys J, November 2000, p. 2235-2251, Vol. 79, No. 5

Models of Post-Translational Protein Translocation

Biomathematics Graduate Program/Department of Statistics, North Carolina State University, Raleigh, North Carolina 27695-8203 USA

Organellar Hsp-70 is required for post-translational translocation into the endoplasmic reticulum and mitochondria. The functional role played by Hsp-70 is unknown. However, two operating principles have been suggested. The power stroke model proposes that Hsp-70 undergoes a conformational change, which pulls the precursor protein through the translocation pore, whereas, in the Brownian ratchet model, the role of Hsp-70 is simply to block backsliding through the pore. A mathematical analysis of both mechanisms is presented and reveals that qualitative differences between the models occur in the behavior of the mean velocity and effective diffusion coefficient as a function of Hsp-70 concentration. An experimental method is proposed for measuring these two quantities that only relies on current experimental techniques.

Biophys J, November 2000, p. 2235-2251, Vol. 79, No. 5
© 2000 by the Biophysical Society   0006-3495/00/11/2235/17  $2.00

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