Axonemal protein which is implicated in axonemal and/or peri- axonemal structure assembly and regulates flagellum assembly and beating and therefore sperm motility. {ECO:0000269|PubMed:31735292, ECO:0000269|PubMed:31735294}. This is the function of TTC29 (tetratricopeptide repeat domain 29, ENSG00000137473).