DNAJA1 is most identical to YDJ1, which may be involved in the transport of certain proteins into the mitochondria and endoplasmic reticulum.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 markedly accumulated with enhanced transcription of several androgen-responsive genes, including Pem (MUC1) and testis-derived transcript (TES). 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.