Probable component of the manchette, a microtubule-based structure which plays a key role in sperm head morphogenesis during late stages of sperm development. Interacts with LRGUK (via guanylate kinase-like domain). Interacts (via C-terminus) with HOOK1 (via coiled-coil region) (By similarity). May interact with FASLG (PubMed:19807924). Belongs to the RIMBP family. It is uncertain whether Met-1 or Met-95 is the initiator.