An analogous role for AIPL1 in transcriptional control has not been demonstrated. However, the ablation or hypomorphic expression of AIPL1 in transgenic mice revealed a role for AIPL1 in cyclic nucleotide signalling. The loss or Dabrafenib reduction of AIPL1 expression in mice leads to the post-transcriptional loss of all three subunits of cGMP phosphodiesterase, a critical component of the phototransduction cascade required for normal vision. Specifically, AIPL1 is required for the stability of the catalytic PDE�� subunit, the loss of which results in the misassembly of the PDE holoenzyme and the rapid proteasomal degradation of all three PDE subunits. We have shown that AIPL1 is critical for proteostasis in photoreceptor cells, not only through its interaction with the Hsp90 chaperone machinery, but also through its interaction with NUB1, a protein that directly binds the proteasome to target the degradation of substrate proteins. Indeed, a recent report identified PDE as an Hsp90 substrate in retina, suggesting that AIPL1 together with Hsp90 function in a chaperone heterocomplex that is essential for PDE biogenesis and maturation. However, the precise molecular mechanisms of how AIPL1 maintains the stability of PDE�� in the biosynthetic pathway and assembly of the PDE holoenzyme is unknown. While the PDE holoenzyme is functional in the photoreceptor outer segments, AIPL1 is compartmentalized predominantly in the remainder of the photoreceptors from the synapse to the inner segment, with an enrichment of AIPL1 detected in the region of the photoreceptor connecting cilium. It is unknown whether the interaction of AIPL1 with PDE is coordinated with the order of events leading to PDE protein translocation to the outer segment via the connecting cilium following protein synthesis in the inner segment. In this study, we identified a novel interaction between AIPL1 and the microtubule endbinding proteins, EB1 and EB3. The EB proteins are microtubule plus-end tracking proteins that exchange rapidly at growing microtubule ends and have an important function in microtubule dynamics. The three conserved members of the EB family are characterised by an N-terminal microtubule-binding calponin homology domain, followed by a coiled coil dimerization domain that overlaps with a unique EB homology domain, and a C-terminal negatively charged amino acid tail. The EB proteins exist as homodimers, ALK5 Inhibitor II although EB1 and EB3 also form a heterodimeric complex and exhibit a significant degree of functional redundancy. The EB proteins interact with numerous +TIP proteins, including the adenomatous polyposis coli tumor suppressor protein, the microtubule-actin crosslinking factor, the mitotic centromere-associated kinesin, the cytoplasmic linker protein of 170 kDa and the large dynactin subunit p150Glued. These associations are important in regulating the reciprocal interaction of microtubules with various cellular structures, including the cell cortex and membranes, the mitotic kinetochore and different cellular organelles. EB complexes at the centrosome are thought to contribute to centrosomal microtubule organization and to stabilize microtubule outgrowth through minus end anchoring. Indeed, EB1 and EB3 have been localized to primary cilia in mammalian cells where they are required for cilia formation and assembly through minus end anchoring at the basal body, thereby facilitating vesicular trafficking to the cilium base. Here, we examined the association of AIPL1 and the EB proteins with the cellular microtubule network, primary cilia in cultured cells and cilia of retinal photoreceptor cells in order to gain further insight into the function of AIPL1.