11-cis-retinal and Brain-Neoplasms

CAMTAs are a group of Ca(2+)/calmodulin binding transcription activators that are implicated in brain tumor suppression, cardiac hypertrophy, and plant sensory responses. The sole fly CAMTA, dCAMTA, stimulates expression of an F-box gene, dFbxl4, to potentiate rhodopsin deactivation, which enables rapid termination of fly visual responses. Here we report that a dCAMTA fragment associated with a full-length protein in co-transfected human embryonic kidney 293 cells. The interaction site was mapped to a region within the DNA-binding CG-1 domain. With this potential dimerization site mutated, the full-length dCAMTA had defective nuclear localization. In transgenic flies, this mutant dCAMTA variant failed to stimulate expression of dFbxl4 and rescue the slow termination of light response phenotype of a dCAMTA null mutant fly. Our data suggest that dCAMTA may function as a dimer during fly visual regulation and that the CG-1 domain may mediate dimerization of CAMTA transcription factors.

Topics: Amino Acid Sequence; Animals; Brain Neoplasms; Calcium-Binding Proteins; Cell Line; Cell Nucleus; Dimerization; Drosophila melanogaster; Drosophila Proteins; Electroretinography; Humans; Models, Biological; Molecular Sequence Data; Mutation; Protein Structure, Tertiary; Rhodopsin; Trans-Activators