BCAP is a centriolar satellite protein and inhibitor of ciliogenesis

The centrosome and cilium are organelles with important roles in microtubule organisation, cell division, cell signalling, embryogenesis, and tissue homeostasis. The two organelles are mutually exclusive. The centriole/basal body is found at the core of the centrosome (centriole) or at the base of the cilium (basal body) and changing which organelle is present in a cell requires modification to the centriole/basal body both in terms of composition and sub-cellular localisation. While many protein components required for centrosome and cilium biogenesis have been described, there are far fewer known inhibitors of ciliogenesis. Here we show that a protein called BCAP and labelled in the sequence databases as ODF2-like (ODF2L) is a ciliation inhibitor. We show that it is a centriolar satellite protein. Furthermore, our data suggest BCAP exists as two isoforms with subtly different roles in inhibition of ciliogenesis. Both are required to prevent ciliogenesis and one additionally controls cilium length after ciliogenesis has completed.