Required for spermatid differentiation. Probably involved in the positioning of the microtubules of the manchette and the flagellum in relation to the membrane skeleton (By similarity). Component of the FTS/Hook/FHIP complex (FHF complex). The FHF complex may function to promote vesicle trafficking and/or fusion via the homotypic vesicular protein sorting complex (the HOPS complex).
Belongs to the hook family.
Cytoplasm > cytoskeleton. Cytoplasm. Localizes to the spermatid manchette during spermiogenesis but is not present in mature spermatozoa (By similarity). Localizes to punctate cytoplasmic foci which do not appear to overlap with early or late endosomes, the endoplasmic reticulum, the Golgi complex, multivesicular bodies (MVBs), lysosomes, or mitochondria. Often found in close association with microtubules.