ZIP4H

ZIP4 homolog (ZIP4H), also known as testis expressed sequence 11 (Tex11) is a 947 amino acid (aa) X chromosome-encoded protein that is selectively expressed in primordial male germ cells. It associates with Nbs1 of the Mre11 protein complex which results in localization to areas of synaptonemal contact between meiotic chromosomes. During meiosis, ZIP4H promotes sister chromatid synapsis and crossover in response to programmed double stranded DNA breaks. ZIP4H deficiency leads to increased spermatocyte apoptosis and male sterility. Alternate splicing in mouse generates an additional isoform with a substitution (aa 691‑707) and truncation (aa 708‑947) at the C-terminus. Within aa 768‑947, mouse ZIP4H shares 44% and 73% aa sequence identity with human and rat ZIP4H, respectively.