Molecular chaperones arc a ubiquitous class of proteins (ha! interact with short stretches of hydrophobic amino acids typically exposed in partially unfolded proteins. Through such interactions, chaperones function in a broad range of physiological processes, facilitating protein folding, protein translocation across membranes, and remodeling of multimeric protein complexes. Hsp70s and J-proteins (often also referred to collectively as DnaJ-like proteins or Hsp40s). which form obligate partnerships, are among the most ubiquitous of the chaperones. In fact, most eukaryotic and prokaryotic genomes encode both multiple Hsp70s and multiple J-proteins. reflecting the fact that they have evolved to function in such a wide variety of processes..