DnaJ/HSP40 Homolog Subfamily B, Member 3 (DNAJB3)

Human DNAJB3 encodes a DnaJ (Hsp40) homolog, subfamily B, member 3 protein. It has a single guanine nucleotide insertion, inducing an open reading frame shift, when compared with its chimpanzee ortholog. Human and chimpanzee DNAJB3 genes are predicted to encode 145 and 224 amino acid proteins, respectively. Interestingly, a comparison of human and chimpanzee DNAJB3 with macaque and mouse orthologs revealed that deletion of a thymine nucleotide near the C-terminus is common in human and chimpanzee. Macaque DNAJB3 and mouse Dnajb3 are specifically expressed in testis. It is unclear whether the chimpanzee DNAJB3 that lacks 18 C-terminal residues compared with the macaque ortholog produces a functional protein, whereas the human DNAJB3 is likely to be inactive as almost half of its residues are missing.