Component of specific cytoplasmic RNA granules involved in post-transcriptional regulation of specific genes: probably acts by binding to specific mRNAs and regulating their translation. Required for lens transparency during lens development, by regulating translation of genes such as CRYBB3 and HSPB1 in the developing lens. Also required during spermatogenesis (By similarity). Found in a mRNP complex, at least composed of TDRD1, TDRD6, TDRD7 and DDX4. Found in a complex containing CABLES1, CDK16 and CDK17. Interacts with CABLES1, CDK17 and PIWIL1 (By similarity). Localizes to cytoplasmic RNA granules (By similarity). Present in chromatoid body (CB) of spermatids (mammalian counterpart of germplasm, pole plasm or polar granules in Drosophila germ cells), also named processing bodies (P-bodies) in somatic cells. Detected in the multilobular cytoplasmic CBs (also called intermitochondrial cementin) in pachytene spermatocytes and as a single perinuclear CB in haploid round spermatids (By similarity). According to PubMed:10727952 localizes preferentially on the periphery of mitochondria. Expressed in brain and testis. Expressed in embryo at 16 dpc onwards. Belongs to the TDRD7 family.