Specifically required during spermatogenesis for flagellum morphogenesis and sperm motility (PubMed:27965440). May be required to suppress the formation of supernumerary axonemes and ensure a correct ultrastructure (PubMed:27965440). Interacts with TUBB and TUBA4A (PubMed:27965440). Interacts with CEP350 (PubMed:27965440). Specifically expressed in tissues containing motile cilia. Expression is activated by FOXJ1. Mice were born at expected Mendelian ratios and appear normal but homozygous males are infertile. Spermatozoa display impaired motility due to defects in the axoneme. Sperm cells show an axonemal loop of the midpiece, supernumerary axonemes and a disrupted axonemal arrangement, as well as defective axonemes along the flagella. Belongs to the CFAP157 family.