The DnaJ family is one of the largest of all chaperone families and has evolved with diverse cellular localization and functions. Presence of a J domain defines a protein as a member of the DnaJ family. DnaJ heat shock induced proteins are derived from Escherichia coli and are under the control of the htpR regulatory protein. DnaJ proteins play a critical role in the HSP 70 chaperone machine by interacting with HSP 70 to stimulate ATP hydrolysis. DnaJ proteins contain cysteine rich regions that are composed of zinc fingers, which form a peptide binding domain responsible for the chaperone function. DnaJ proteins are important mediators of proteolysis and are involved in the regulation of protein degradation, exocytosis and endocytosis. DnaJC8 (DnaJ (Hsp 40) homolog, subfamily C, member 8), also known as SPF31 or HSPC331, is a 253 amino acid protein that is suggested to have a potential role as a cochaperone in RNA processing-related processes.