IQ Motif Containing Protein H (IQCH)

Using cDNA microarray analysis to identify genes expressed in adult but not fetal testis, Yin et al. (2005) cloned IQCH, which they designated NYD-SP5. The deduced 1,027-amino acid protein contains a carbamate kinase-like domain, an IQ motif, a zinc-dependent exopeptidase domain, and an LDH C-terminal domain-like sequence.

IQCH shares 68% and 57% amino acid identity with its mouse and rat orthologs, respectively. RT-PCR detected IQCH expression in adult testis, but not in 15 other tissues examined. IQCH was expressed in normal human spermatozoa, but not in testis of patients with Sertoli cell-only syndrome . In situ hybridization of mouse testis detected Iqch in spermatocytes and spermatids only