The GAL4-based yeast two-hybrid system (HybriZAP, Stratagene) was used for identifying binary protein-protein interaction partners of POC1B. The construct encoding the full-length POC1B and the three constructs encoding fragments of POC1B were fused to a DNA binding domain (GAL4-BD) and used as bait for screening a human oligo-dT-primed retinal cDNA library. The yeast strain PJ69-4A, which carries the HIS3 (histidine), ADE2 (adenine), and LacZ (β-galactosidase) reporter genes, was used as a host. Interactions were analyzed by assessment of reporter gene (HIS3 and ADE2) activation via growth on selective media and β-galactosidase colorimetric filter lift assays (LacZ reporter gene). cDNA inserts of clones containing putative interaction partners were confirmed by Sanger sequencing.