Models of post-translational protein translocation.
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.
Elston
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Biomathematics Graduate Program/Department of Statistics, North Carolina State University, Raleigh, North Carolina 27695-8203, USA. elston@stat.ncsu.edu
D000818:Animals; D001693:Biological Transport, Active; D055592:Biophysical Phenomena; D001703:Biophysics; D004721:Endoplasmic Reticulum / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*
D018840:HSP70 Heat-Shock Proteins; D011506:Proteins