Thought to have an important role in cilia formation and cilia-mediated chemosensation. Involved in the docking of other MKS/MKSR proteins localized to the transition zone of the cilia. Localizes to the transition zone. Expressed at the transition zone at the base of cilia. Expressed in ciliated sensory neurons, including the amphid neurons in the head. Defective cilia sensory function. Abnormal dye filling (Dyf) in the ASI neuron and chemotaxis behavior. Shorter cilia lengths in a subset of ciliary neurons. Aberrant localization of other cilia-expressed proteins. An X-box element in the predicted promoter region was identified consistent with other cilia-related genes. Belongs to the RPGRIP1 family.