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. Required for normal axoneme assembly in sperm flagella, normal sperm tail formation and for male fertility. 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+). Interacts with the HSP70 proteins HSPA1L and HSPA8 (PubMed:24787902). May form a complex with CAMK4 and HSP70 (By similarity). 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. The IQ domain mediates interaction with calmodulin when cellular Ca(2+) levels are low. Belongs to the DRC9 family.