This gene encodes a member of the DnaJ or Hsp40 (heat shock protein 40 kD) family of proteins. DNAJ family members are characterized by a highly conserved amino acid stretch called the 'J-domain' and function as one of the two major classes of molecular chaperones involved in a wide range of cellular events, such as protein folding and oligomeric protein complex assembly. 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. Alternative splicing results in multiple transcript variants.

DnaJ protein homolog 1;DNAJ1;DNAJB1;hDj 1;Hdj1;Heat shock 40 kDa protein 1;Heat shock protein 40;Hsp40;HSPF1;Human DnaJ protein 1;Sis1