Seems to be a major component of sperm tail outer dense fibers (ODF). ODFs are filamentous structures located on the outside of the axoneme in the midpiece and principal piece of the mammalian sperm tail and may help to maintain the passive elastic structures and elastic recoil of the sperm tail (By similarity). Self-associates. Associates with microtubules and forms a fibrillar structure partially linked to the microtubule network (By similarity). Belongs to the ODF2 family.