Transmembrane 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. Required for ciliogenesis and sonic hedgehog/SHH signaling (By similarity). Part of the tectonic-like complex (also named B9 complex). Interacts with TMEM107. Localizes to the transition zone of primary cilia; SEPT2 is required for localization to the transition zone. Belongs to the TMEM231 family. Extended N-terminus.