Major structural component of sperm fibrous sheath. May play a role in sperm motility (By similarity). Interacts with PRKAR1A and PRKAR2A. Interacts with ENO4. Localizes to the principle piece of the sperm flagellum. Expressed in flagella of epididymal sperm. RI-alpha binding site, predicted to form an amphipathic helix that is required for binding to Prkar1a. Belongs to the AKAP110 family.