Component of the nexin-dynein regulatory complex (N-DRC), a key regulator of ciliary/flagellar motility which maintains the alignment and integrity of the distal axoneme and regulates microtubule sliding in motile axonemes. Binds calmodulin when cellular Ca(2+) levels are low and thereby contributes to the regulation of calcium and calmodulin-dependent protein kinase IV (CAMK4) activity; contributes to the regulation of CAMK4 signaling cascades (By similarity). Required for normal axoneme assembly in sperm flagella, normal sperm tail formation and for male fertility (PubMed:24362311, PubMed:24849454). Component of the nexin-dynein regulatory complex (N-DRC) (By similarity). Interacts (via IQ domain) with CALM when calcium levels are low. Does not interact with CALM in the presence of Ca(2+) (PubMed:24849454). Interacts with the HSP70 proteins HSPA1L and HSPA8 (By similarity). May form a complex with CAMK4 and HSP70 (Probable). First detected in the cytoplasm of pachytene spermatocytes. Colocalizes with alpha-tubulin at the manchette in developing spermatids. Detected in the flagellum of mature testicular spermatozoa, and in the flagellum and post-acrosomal region of the head of epididymal spermatozoa. Detected in cilia in trachea and oviduct. Detected in testis (PubMed:24362311, PubMed:24849454). Also detected in oviduct (at protein level) (PubMed:24849454). Detected in testis (PubMed:24362311, PubMed:24849454). Also detected in oviduct and trachea (PubMed:24849454). First detected in testis 17 days after birth when pachytene spermatocytes are seen in testes. Expression remains high during the first three weeks after birth and in adults (at protein level). The IQ domain mediates interaction with calmodulin when cellular Ca(2+) levels are low. No obvious phenotype, except complete male sterility (PubMed:24362311, PubMed:24849454). Female fertility is not altered (PubMed:24849454). Early spermiogenesis defective 12d (esgd12d) is caused by mutations disrupting this gene. Affected male mice display complete loss of fertility; their sperm cells lack tails and are nonmotile. Belongs to the DRC9 family.