Cellular component

cilial base, cilium base, flagellar base, flagellum base

Area of the cilium (also called flagellum) where the basal body and the axoneme are anchored to the plasma membrane. The ciliary base encompasses the distal part of the basal body, transition fibers and transition zone and is structurally and functionally very distinct from the rest of the cilium. In this area proteins are sorted and filtered before entering the cilium, and many ciliary proteins localize specifically to this area.

Due to resolution issues, researchers are often unable to assign protein localization to more specific ciliary compartments such as the basal body, transition fibers or transition zone, and instead refer to 'ciliary base'. The terms GO:0036064 'ciliary basal body', GO:0097539 'ciliary transition fiber' and GO:0035869 'ciliary transition zone' represent strictly defined compartments at the ciliary base and should be used for annotation whenever possible. Also, note that cilia and eukaryotic flagella are deemed to be equivalent.