Involved in spermatozoa motility (PubMed:30122540, PubMed:30122541). May also regulate cilium motility through its role in the assembly of the axonemal radial spokes (By similarity). Isoform 1 is highly expressed in testis and, at lower levels, in lung. Very low levels are detected in kidney and brain (PubMed:30122540). In testis, expressed in spermatozoa (at protein level) (PubMed:30122540, PubMed:30122541). Isoform 2 is not detected in testis, lung, kidney, nor in brain (PubMed:30122540). The disease is caused by variants affecting the gene represented in this entry.