title: A potential dimerization region of dCAMTA is critical for termination of fly visual response.
abstract: 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.
authors.affiliation: Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
authors.forename: Ping
authors.initials: P
authors.lastname: Gong
authors.forename: Junhai
authors.initials: J
authors.lastname: Han
authors.forename: Keith
authors.initials: K
authors.lastname: Reddig
authors.forename: Hong-Sheng
authors.initials: HS
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001932:Brain Neoplasms / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000737:chemistry*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D019281:Dimerization; D029721:Drosophila Proteins / Q000737:chemistry* / Q000502:physiology; D004331:Drosophila melanogaster; D004596:Electroretinography; D006801:Humans; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D017434:Protein Structure, Tertiary; D012243:Rhodopsin / Q000737:chemistry; D015534:Trans-Activators / Q000737:chemistry* / Q000502:physiology
chemical_list: C522742:CAMTA protein, Drosophila; C487554:CAMTA1 protein, human; D002135:Calcium-Binding Proteins; D029721:Drosophila Proteins; D015534:Trans-Activators; D012243:Rhodopsin