Plant Hsp90 and Its Partner Proteins

The 90 kD heat shock protein, hsp90, is a ubiquitous molecular chaperone with vital roles in cell regulation and signal transduction. Hsp90 homologues have been identified in several plant species. A detailed understanding of hsp90 functions in plant cells is currently not available, however, studies of hsp90 expression suggest functions related to plant growth and development and to environmental stress. Hsp90, in animal and yeast cells, promotes foldinglactivation of the client proteins through cooperation with its co-chaperones, which together constitute a hsp90-based chaperone system. A hsp90-based chaperone system has also been identified in plant cells. The components of the plant complex identified so far appear to be similar to those found in animal and yeast cells. It remains to be seen if the hsp90 chaperone system plays a critical role in signaling pathways of plant cells, as it does in the animal cells.