Microtubule inner protein (MIP) part of the dynein-decorated doublet microtubules (DMTs) of multiciliated respiratory cells and the distal singlet microtubules of monoflagellated spermatozoa. Forms both spirals and striations within ciliary microtubules. May stabilize the protofilaments to which they are bound.
Subcellular locations: Cytoplasm, Cytoplasmic vesicle, Secretory vesicle, Acrosome, Cytoplasm, Cytoskeleton, Cilium basal body, Cell projection, Cilium, Flagellum, Nucleus, Cytoplasm, Cytoskeleton, Cilium axoneme
In caudal sperms localizes onto sperm head. Is also present on midpiece and principle piece of sperm tails. Acrosome and sperm tail localization is regulated by Y-chromosome.