Involved in assembly and/or maintenance of motile cilia. Required during spermatogenesis for axoneme elongation. Necessary for optimal function of the chordotonal (hearing) organs. Detected in ciliated sensory neurons at all stages of development, and in adult testis. In the testis, expressed in spermatocytes and elongating spermatids. Viable with no gross coordination or gravitaxis defects. Males are sterile with complete absence of mature spermatozoa, while female fertility is unaffected. In developing spermatids, axonemes fail to elongate normally and sperm individualization is disrupted. Tubulin glycylation of spermatid axonemes is abnormal. Hearing is moderately impaired. Belongs to the CFAP97 family.