Chaperones folding pathway

This strategy is somewhat reminescent of the biological folding pathways of natural polypeptides that use selective interactions with effectors (Ca2+, chaperone proteins, etc.) to start the nucleation of the secondary structures [5] and has been used successfully to prepare well defined peptide nanostructures by several groups. 

What is the likelihood that SecB is the sole secretion-related chaperone If one assumes that the efficient export of each envelope protein requires a chaperone, then the low abundance of SecB and the SecB-independent export of several envelope proteins argue that there must be additional secretion-related chaperones. However, there is no a priori reason to expect that the efficient export of each secretory protein requires a chaperone, since the folding pathways or other properties of different precursors are likely to be variable. In fact, the observation that minor changes in the primary sequence of preMBP can virtually eliminate the SecB dependence of this protein (Collier and Bassford, 1989 Section IX, A) challenges the assumption that secretion of each envelope protein must be chaperoned by SecB or a SecB analog. 

Protein folding pathways, (a) Chaperone-independent folding. 

Oionisi HM, Checa SK, Krapp AR et al. Cooperation of the DnaK and GroE chaperone systems in the folding pathway of plant ferredoxin-NADP reductase expressed in Escherichia coli. Eur J Biochem 1998 251(3) 724-728. 

Craig, E.A. (1993).Chaperones—helpers along the pathways to protein folding. Science 260, 1902-1903. 

Langer, T., Lu., C, Echols, H., Flanagan, J, Hayer, M.K., Hartl, F.-U. (1992). Successive action of Dnak, DnaJ, GroEL along the pathway of chaperone mediated protein folding. Nature 356, 683-689. 

Exit from the ER may be the rate-limiting step in the secretory pathway. In this context, it has been found that certain proteins play a role in the assembly or proper folding of other proteins without themselves being components of the latter. Such proteins are called molecular chaperones a number of important properties of these proteins are listed in Table 46—5, and the names of some of particular importance in the ER are listed in Table 46-6. Basically, they stabilize unfolded... 

The sequence for delivery of copper ions to SOD1 passes from the copper transporter (Ctr) by an unknown pathway to the copper chaperone for SOD1 (CCS) and by a studied pathway from CCS to SOD1. The CCS protein has been studied structurally and found to be similar to other copper chaperones such as those discussed above—Atxl and Atoxl (Hahl). Copper chaperone for superoxide dismutase (CCS) differs from other copper metallochaperones in that it folds into three functionally distinct protein domains with the N-terminal end of domain I... 

---