Induces mitochondrial fragmentation, possibly by promoting DNM1L-dependent fission and may play a role in mitochondrial morphogenesis during spermatogenesis. Interacts with isoform 1 and isoform 2 of GGN. Testis-specific. In the testis, expressed only in germ cells and not in somatic cells. Expression starts in late primary spermatocytes in stage X-XII tubules and gradually increases towards step 1-3 spermatids in stage I-III tubules. Expression then declines continuously and disappears after step 7 spermatids in stage VII tubules (at protein level). Specifically expressed in germ cells tightly related to meiosis. In the developing mouse testis, it is not detected in the testes of 14-day-old mice, when pachytene spermatocytes are still in their early stage, while it is detected in tubules with late pachytene spermatocytes and spermatids in the testes of 21-day-old mice. The N-terminal domain is required for targeting to the mitochondrion.