Involved in vesicle trafficking and required for ciliogenesis, formation of primary non-motile cilium, and recruitment of RAB8A to the basal body of primary cilium (PubMed:19625297). Component of the tectonic-like complex, a complex localized at the transition zone of primary cilia and acting as a barrier that prevents diffusion of transmembrane proteins between the cilia and plasma membranes (PubMed:22179047). Involved in neuronal differentiation (PubMed:23658157). As a positive modulator of classical Wnt signaling, may play a crucial role in ciliary signaling during cerebellum embryonic development (PubMed:21623382). Self-associates (By similarity). Part of the tectonic-like complex (also named B9 complex) (PubMed:22179047). Interacts with MKS1 (PubMed:21565611). Interacts with NPHP1; probably as heterodimers and/or AHI1(2):NPHP1(2) heterotetramers (PubMed:18633336). Interacts (via SH3 domain) with the dynamin GTPase DNM2 (By similarity). Interacts with HAP1; probably as AHI1(2):HAP1(2) heterotetramers (By similarity) (PubMed:23658157). Interacts with RAB8A (PubMed:19625297). Interacts with CEND1 (PubMed:23658157). Interacts with SPATA7 (PubMed:29899041). In the retinal photoreceptor cell layer, localizes at the connecting cilium. Expressed in the retina (at protein level) (PubMed:29899041). Highly expressed in the brain (PubMed:12186888, PubMed:15467982). Highly expressed in the testis (PubMed:12186888). Expressed in the kidney, thymus, heart, lung, spleen (PubMed:12186888). Weakly expressed in the liver, stomach, pancreas, and embryo (PubMed:12186888). Strongly expressed during periods of both cortical and cerebellar development (PubMed:15467982). First detected at 7 days post conception (dpc) and is also present at 11 dpc, 15 dpc and 17 dpc with the highest level at 15 dpc. Expression in whole brain is detected from 14 dpc to adult. Expression in cerebellum appears maximal at 18 dpc and postnatal days 5 (P5), whereas expression in cerebral cortex appears maximal at 16 dpc and 18 dpc. Mutant mice, when surviving after birth, show retarded growth during the postnatal period, but do not develop severe cerebellar vermis hypoplasia or ataxia associated with cerebellar dysfunction (PubMed:23658157). Adult homozygous knockout mice have a small body size, with slightly reduced brain size compared with wild-type and heterozygous littermates. The overall brain morphology appears normal except for a smaller cerebellum and underdeveloped vermis with a mildly defective foliation pattern. Vermian lobules VI and VII appear fused, whereas lobule V appears smaller and underdeveloped at 3 weeks of age. Overall, the cerebellum is slightly hypoplastic (PubMed:21623382). Is targeted by provirus integrations. This deregulation contributes to tumor development.