The ciliary pocket

Cilia are fascinating highly conserved organelles shared by very different organisms from unicellular eukaryotes to vertebrates where they are involved in motility and sensory functions. In vertebrates, the function of the primary cilium, a unique nonmotile cilium found at the surface of most cell types during development, remained mysterious during 40 years until its crucial function in the control of key signaling cascades during development and its involvement in complex genetic disorders now called ciliopathies were uncovered. Recent studies have focused on a specific membrane domain found at the base of primary cilia in most cell types which was already mentioned in the first descriptions of these cilia but did not raise much interest during 50 years. This membrane domain, the 'ciliary pocket', also found at the base of some motile cilia, may act as a platform for cilia-associated vesicular trafficking and as an interface with the actin cytoskeleton but also likely in additional important functions which remain to be discovered.