The DnaJ family is one of the largest of all the chaperone families and has evolved with diverse cellular localization and functions. The presence of the J domain defines a protein as a member of the DnaJ family. DnaJ heat shock induced proteins are from the bacterium Escherichia coli and are under the control of the htpR regulatory protein. The DnaJ proteins play a critical role in the HSP 70 chaperone machine by interacting with HSP 70 to stimulate ATP hydrolysis. DnaJ proteins are important mediators of proteolysis and are involved in the regulation of protein degradation, exocytosis and endocytosis. DnaJC14 (DnaJ homolog subfamily C member 14), also known as DRIP78 (Dopamine receptor-interacting protein of 78 kDa) and HDJ3 (Human DnaJ protein 3), is a 702 amino acid endoplasmic reticulular membrane protein that contains one J domain. DnaJC14 regulates the export of target proteins, such as the dopamine D1 receptor (D1DR), from the endoplasmic reticulum to the cell surface.