Myristoyl-binding protein that acts as a cargo adapter: specifically binds the myristoyl moiety of a subset of N-terminally myristoylated proteins and is required for their localization. Binds myristoylated NPHP3 and plays a key role in localization of NPHP3 to the primary cilium membrane. Does not bind all myristoylated proteins. Probably plays a role in trafficking proteins in photoreceptor cells. Found in a complex with ARL3, RP2 and UNC119B; RP2 induces hydrolysis of GTP ARL3 in the complex, leading to the release of UNC119B. Interacts with NPHP3 (when myristoylated). Interacts with CYS1 (when myristoylated). Interacts with MACIR; interaction only takes place when UNC119B is not liganded with myristoylated proteins. Enriched at the transition zone and extended into the proximal end of the cilium. Adopts an immunoglobulin-like beta-sandwich fold forming a hydrophobic cavity that capture N-terminally myristoylated target peptides. Phe residues within the hydrophobic beta sandwich are required for myristate binding (PubMed:22085962). Belongs to the PDE6D/unc-119 family.