This family consists of several radial spoke protein 3 (RSP3) sequences. Eukaryotic cilia and flagella present in diverse types of cells perform motile, sensory, and developmental functions in organisms from protists to humans. They are centred by precisely organized, microtubule-based structures, the axonemes. The axoneme consists of two central singlet microtubules, called the central pair, and nine outer doublet microtubules. These structures are well-conserved during evolution. The outer doublet microtubules, each composed of A and B sub-fibers, are connected to each other by nexin links, while the central pair is held at the centre of the axoneme by radial spokes. The radial spokes are T-shaped structures extending from the A-tubule of each outer doublet microtubule to the centre of the axoneme. Radial spoke protein 3 (RSP3), is present at the proximal end of the spoke stalk and helps in anchoring the radial spoke to the outer doublet. It is thought that radial spokes regulate the activity of inner arm dynein through protein phosphorylation and dephosphorylation.