Required for correct axoneme development in spermatozoa (PubMed:21715716, PubMed:28619825). Important for normal development of the manchette and sperm head morphology (PubMed:28619825). Essential for male fertility (PubMed:21715716, PubMed:28619825). Plays a role in localization of the intraflagellar transport protein IFT20 to the manchette, suggesting function as an adapter for dynein-mediated protein transport during spermatogenesis. Also plays a role in bone growth where it seems to be required for normal osteoblast differentiation (PubMed:28619825). Interacts (via C-terminus) with IFT20 (PubMed:19889948). Interacts with DYNC1I2 (PubMed:28619825). Shows dynamic localization in developing spermatozoa (PubMed:19889948). Localizes to the manchette in step 10-12 elongating spermatids, where it is mainly found on the basal side below the perinuclear ring (PubMed:19889948, PubMed:28619825). Detected in the basal body and neck area of step 13-14 spermatids (PubMed:19889948). Localizes to the midpiece of the sperm tail in step 15-16 spermatids (PubMed:19889948). During the epididymal transport of spermatozoa, expression in the sperm tail reduces and becomes concentrated at the distal part of the midpiece (PubMed:19889948). Detected in the Golgi apparatus of late spermatocytes and round spermatids (PubMed:19889948). Detected in the cytoplasm of Sertoli cells (PubMed:19889948). A number of isoforms are produced. Highly expressed in testis, where it primarily localizes to late spermatocytes, round spermatids and elongating spermatids (at protein level) (PubMed:19889948, PubMed:29339787). Found in Sertoli cells of the testis (at protein level) (PubMed:19889948). Expressed at lower levels in epididymis (at protein level) (PubMed:19889948, PubMed:29339787). Detected in lung, brain, liver and kidney (PubMed:19889948, PubMed:29339787). Also detected in bone, cartilage, trachea, pituitary gland and eye (PubMed:29339787). Expressed in osteoblasts and chondrocytes (PubMed:29339787). Shows increasing expression levels in testis during postnatal stages, reaching highest levels by postnatal day 50. In testis, first detected in pachytene spermatocytes (stage VII), reaching peak expression in meitotically dividing spermatocytes (stage XII). Lethality occurs at approximately 3 weeks of age, accompanied by severe hydrocephaly. Weight at birth is similar to wild type but subsequently there is significant growth retardation. Bone mineralization is reduced in the vertebral column and hindlimbs, associated with decreased bone strength. Bone length and skull thickness is also slightly reduced. Trabecular bone density is reduced, along with reduced trabecular number and increased open porosity. Expression of the osteoblast marker genes RUNX2, BGLAP/OCN and COL1A1/COL1 is reduced in bone tissue. Expression of SP7/OSX and ALPL is also reduced in cultured calvarial osteoblasts. Osteoclast differentiation does not appear to be affected. No obvious effects on cilia length or axonemal structure.