Flagellar radial spokes contribute to the regulation of dynein arm activity and thus the pattern of flagellar bending. They consist of a thin stalk, which is attached to the a subfiber of the outer doublet microtubule, and a bulbous head, which is attached to the stalk and appears to interact with the projections from the central pair of microtubules (PubMed:16507594). Binds calmodulin in a calcium-dependent manner (PubMed:14871938). Radial spoke. Asymmetrically dimethylated at Arg-104, Arg-260, Arg-453, Arg-538 and Arg-615 during flagellum resorption. Probably methylated by PRMT1. Absence of radial spokes. In-gel analysis assays show kinase-like activity in vitro. However, such activity has not been confirmed using recombinant protein. Belongs to the dpy-30 family.