Cytoskeletal linker that plays a central role in the flagellum cell motility. Required for directional cell motility. Plays a role as part of a dynein regulatory system that regulates flagellar beat in response to signals from the central pair apparatus and radial spokes in procyclic cells. Also plays an essential role in the bloodstream form of the trypanosomes as its silencing is lethal for the circulating form. Associated with the cytoskeleton. Localized to the site of attachment of the flagellum to the subpellicular cytoskeleton. Also localized in the flagellum of the bloodstream form trypanosomes. Procyclic parasite mutants lacking trypanin exhibit a motility defect indicative of abnormal dynein regulation, but have an actively beating flagellum and are able to spin and tumble in place. However, bloodstream form mutants lacking trypanin exhibit a severe growth defect and are not viable. They revealed a failure of cytokinesis. Belongs to the DRC4 family.