Required for cilia biogenesis. Appears to function within the multiple intraflagellar transport complex B (IFT-B). Key regulator of hedgehog signaling. Interacts with CLU/clusterin. Interacts with UBXN10; the interaction is direct. Expressed in all tissues tested including heart, kidney, skeletal muscle, eye, liver, ovary, oviduct, testes, lung and brain. Elevated levels in multiciliated cells such as the bronchioles of the lungs, ependymal cells of the brain and cells with a single primary cilia of heart and kidney. E9.5 embryos are still viable but die thereafter. Mutant embryos are runted, have exhibit enlarged pericardial sacs, and defects in neural tube development. There is a complete absence of cilia in E9.5 embryos. Sonic hedgehog (SHH) signaling is severely disrupted with down-regulation of PTCH1 and GLI1. Belongs to the CLUAP1 family.