Figure 8.

Two Possible Models for the Relationship between the cpHsc70 and the Hsp93/Tic40 Systems.

(A) The cpHsc70 and Hsp93/Tic40 systems may function as one complex, for example, with cpHsc70 assisting the assembly of the Hsp93/Tic40 system.

(B) The cpHsc70 and Hsp93/Tic40 systems may function in parallel, for example, by both independently associating and facilitating the translocation of precursors across the inner membrane. Therefore, at any given time, a precursor could be associated with either one, or both, chaperones as depicted in the figure. The red and blue regions of the line indicate the transit peptide and mature regions of a precursor protein, respectively. Since it is not known how Hsp93 and cpHsc70 bind to a precursor, they are placed arbitrarily on the precursor.