Adapter that functions to localize a calcium-sensitive signal transduction machinery in sperm to a calcium-permeable ion channel (PubMed:15385169). Microtubule inner protein (MIP) part of the dynein-decorated doublet microtubules (DMTs) in cilia axoneme, which is required for motile cilia beating (By similarity). Binds calmodulin via its IQ domain. Interacts with TRPC1, TRPC2, TRPC5, but not TRPC3 (PubMed:15385169). Interacts with CFAP45 (By similarity). Sperm acrosomal crescent and flagellar principal piece. High expression in testis and vomeronasal organ and lower expression in ovary, heart, lung, and brain. Not expressed in other tissues. The IQ motif is involved in calmodulin binding.