This gene encodes a member of the DnaJ or Hsp40 (heat shock protein 40 kD) family of proteins. The encoded protein is a molecular chaperone that stimulates the ATPase activity of Hsp70 heat-shock proteins in order to promote protein folding and prevent misfolded protein aggregation. The encoded protein may also inhibit apoptosis. Peritoneal macrophages derived from homozygous knockout mice for this gene exhibit impaired heat tolerance. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Apr 2015]