Microtubule-associated protein regulating the stability and length of the microtubule-based axoneme of photoreceptors. Required for the differentiation of photoreceptor cells, it plays a role in the organization of the outer segment of rod and cone photoreceptors ensuring the correct orientation and higher-order stacking of outer segment disks along the photoreceptor axoneme (By similarity). Interacts (via the doublecortin domains) with microtubules. Interacts with RP1L1 (By similarity). Interacts with MAK (By similarity). Specifically localized in the connecting cilia of rod and cone photoreceptors. The doublecortin domains, which mediate interaction with microtubules, are required for regulation of microtubule polymerization and function in photoreceptor differentiation.