Abstract

Proteins involved in centriole duplication appear to exist and function in sub-complexes; Sas6 binds to phosphorylated Ana2 to initiate pro-centriole formation; Sas4 interacts with centriolar microtubules; the Cep135:Ana1:Asl network promotes centriole to centrosome conversion enabling recruitment of Plk4 and peri-centriolar material. Here, we investigate Rcd4, a previously uncharacterised Drosophila centriolar protein and show that rcd4 mutants exhibit fewer centrioles in many tissues, aberrant mitoses in embryos, and reduced basal bodies in sensory organs leading to uncoordination. Importantly, we demonstrate that Rcd4 interacts with Ana3 to form yet another sub-complex involved in centriole biogenesis. Neither of the proteins participate directly in the mitotic conversion of centrioles to centrosome, but both are required to load Ana1, which is essential for such conversion.