The heat shock proteins (HSPs) comprise a group of highly conserved, abundantly expressed proteins with diverse functions, including the assembly and sequestering of multiprotein complexes, transportation of nascent poly-peptide chains across cellular membranes and regulation of protein folding. Heat shock proteins (also known as molecular chaperones) fall into six general families: HSP 90, HSP 70, HSP 60, the low molecular weight HSPs, the immunophilins and the HSP 110 family. The low molecular weight family includes HSP 10, HSP 20, HSP 27 (Heme Oxygenase 1), HSP 32 and HSP 40. HSP 20 occurs in two complex sizes, dimers and multimers. It is related to stress proteins and occurs most abundantly in skeletal muscle and heart. HSP 20 is considerably shorter at the C-terminus and less polar than other small heat shock proteins.