The E. coli heat-shock protein DnaJ has been implicated in protein folding, proteolysis, phosphorylation, and replication of phage. By screening a human umbilical vein endothelial cell cDNA expression library with a monoclonal antibody that reacts specifically with human endothelial cells and monocytes, Chellaiah et al. (1993) isolated cDNAs encoding DNAJA1, which they named HDJ2. The deduced 397-amino acid DNAJA1 protein is 32% identical to E. coli DnaJ, with the highest identity in the N-terminal region. Among the known DNAJ homologs in S. cerevisiae, DNAJA1 is most identical to YDJ1, which may be involved in the transport of certain proteins into the mitochondria and endoplasmic reticulum.

By immunohistochemical analysis and Western blot analysis, Terada et al. (2005) showed that Dja1 was expressed in mouse testis and prostate.

Terada et al. (2005) found that loss of Dja1 in mice led to severe defects in spermatogenesis that involved aberrant androgen signaling. Transplantation experiments with fluorescence-tagged spermatogonia into Dja1 -/- mice revealed a primary defect of Sertoli cells in maintaining spermiogenesis at steps 8 and 9. In Sertoli cells of Dja1 -/- mice, the androgen receptor (313700) markedly accumulated with enhanced transcription of several androgen-responsive genes, including Pem (MUC1; 158340) and testis-derived transcript (TES; 606085). Disruption of Sertoli-germ cell adherens junctions was also evident in Dja1 -/- mice. Experiments with Dja1 -/- fibroblasts and primary Sertoli cells indicated aberrant androgen receptor signaling.