Heat shock protein DnaJ proteins

Gamer, J., Bujard, H., Bukua, B. (1992). Physical interaction between heat shock proteins DnaK, DnaJ, CJtpE the bacterial heat shock transcription factor sigma 32. Cell 69, 833-842. 

Many of the chaperones double as heat shock-proteins (Hsp). When a cell is put under stress that can cause proteins to denature, such as too high a temperature, it produces heat-shock proteins. Their names are abbreviated to Hsp plus their subunit molecular mass in kDa. Hsp70, for example, is a ubiquitous heat-shock protein in eukaryotes. It is known in E. coli as DnaK for historical reasons because it was first discovered from a supposed role in DNA replication. Hsp70 is also important in protein trafficking and the conveying of proteins across membranes, because the denatured state is important in these processes. In protein biosynthesis, the unfolded state of the nascent polypeptide chain is passed on to DnaK, which maintains it in an extended form. The chain, under the influence of ATP and co-chaperones such as DnaJ and GrpE, is handed over to GroEL. 

Blumberg, H., and Silver, P. A. (1991). A homologue of the bacterial heat-shock gene DnaJ that alters protein sorting in yeast. Nature (London) 349, 627-630. 

Liberek, K., Georgopoulos, C., and Zylicz, M. (1988). Role of the Escherichia coli DnaK and DnaJ heat shock proteins in the initiation of bacteriophage lambda DNA replication. Proc. Natl. Acad. Sci. U.S.A. 85, 6632—6636. 

Sadler, I., Chiang, A., Kurihara, T., Rothblatt, J., Way, J., and Silver, P. (1989). A yeast gene important for protein assembly into the endoplasmic reticulum and the nucleus has homology to DnaJ, an Escherichia coli heat shock protein. J. Cell Biol. 109, 2665-2675. 

Wickner, S. H. (1990). Three Escherichia coli heat shock proteins are required for PI plasmid DNA replication Formation of an active complex between E. coli DnaJ protein and the PI initiator protein. Proc. Nall. Acad. Sci. U.S.A. 87, 2690-2694. 

---