Figure 5

FIZ1 is part of retinal protein complexes that bind to NRE, BAT-1 and Ret-4 elements from the Rho proximal promoter. The [³²P]-labeled oligonucleotide probes NRE, BAT-1, and Ret-4 were incubated with bovine retinal nuclear protein extract (NucEx), followed by nondenaturing PAGE. A) NRE: The binding site for the NRL bZIP domain is shown in bold face type. Removal of a shifted complex by antibody to FIZ1 is indicated (arrow). B) BAT-1: The binding sites for the Homeo-Domain of CRX are shown in bold face type. Removal of a shifted complex by antibody to FIZ1 is indicated (arrow). C) Ret-4: The core binding site for the CRX-HD is shown in bold face type. Removal of a shifted complex by antibody to FIZ1 is indicated (arrow). Presence of components are as indicated (+/-). Competition for each probe with unlabeled oligonucleotide validated the specificity of the band shift. Anti-FIZ1, or preserum IgG, was added after complex formation.