Plant Hsp70 molecular chaperones: Protein structure, gene family, expression and function

The Hsp70 molecular chaperones of plants are encoded by a multi‐gene family whose members are developmentally regulated and differentially expressed in response to temperature stress and other conditions that interrupt normal protein folding or favor protein denaturation. Under non‐stressful conditions, Hsp70 cognates function in concert with a variety of co‐chaperones to facilitate folding of de novo synthesized proteins, assist in transport of precursor proteins into organelles and to help target damaged proteins for degradation. Stress‐induced Hsp70s function to mitigate aggregation of stress‐denatured proteins and to refold non‐native proteins restoring their biological function through iterative cycles of adenine nucleotide hydrolysis‐dependent peptide binding and release. Much of what is known about how plant Hsp70s function comes from the study of Hsp70s from other types of organisms. Owing to their unique biology, much remains to be learned about the many functions Hsp70s play in plants.