Expanding the cellular molecular chaperone network through the ubiquitous cochaperones

Cellular environments are highly complex and contain a copious variety of proteins that must operate in unison to achieve homeostasis. To guide and preserve order, multifaceted molecular chaperone networks are present within each cell type. To handle the vast client diversity and regulatory demands, a wide assortment of chaperones are needed. In addition to the classic heat shock proteins, cochaperones with inherent chaperoning abilities (e.g., p23, Hsp40, Cdc37, etc.) are likely used to complete a system. In this review, we focus on the HSP90-associated cochaperones and provide evidence supporting a model in which select cochaperones are used to differentially modulate target proteins, contribute to combinatorial client regulation, and increase the overall reach of a cellular molecular chaperone network. This article is part of a Special Issue entitled: Heat Shock Protein 90 (HSP90).