Basal body protein required in multiciliate cells to align and maintain cilia orientation in response to flow. May act by mediating a maturation step that stabilizes and aligns cilia orientation. Not required to respond to planar cell polarity (PCP) or flow-based orientation cues. Localizes to a polar structure adjacent to the basal body. Multiciliated cells. Up-regulated by foxj1 during motile cilia formation. Cilia in multiciliate cells are motile but fail to produce flow. Multiciliated cells are present in the normal number, cilia of normal length and of normal density. They are however misoriented. Belongs to the BBOF1 family.