title: FHX.L and FHX.S, two isoforms of the human fork-head factor FHX (FOXJ2) with differential activity.
abstract: Many biological phenomena are dependent on mechanisms that fine-tune the expression levels of particular genes. This can be achieved by altering the relative activity of a single transcription factor, by post-translational modifications or by interaction with regulatory molecules. An alternative mechanism is based on competition between two or more differently active isoforms of the same transcription factor. We found that FHX, a recently characterized human fork-head transcriptional activator, may show such a mechanism for balancing its activity by expressing two differently sized isoforms, FHX.S and FHX.L, encoded by a single gene located on human chromosome 12. FHX. L and FHX.S showed different transcriptional capacities, the larger form, FHX.L, behaving as the more potent transactivator. A transactivation domain of the acidic type present only in FHX.L would account for this functional difference. The relative concentrations of these two FHX isoforms appear to vary in a number of cell types, a circumstance that may regulate the final activity of this transcription factor.
authors.affiliation: Centro de Investigaciones Biológicas, CSIC, Velázquez 144, Madrid, 28006, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Pérez-Sánchez
authors.forename: C
authors.initials: C
authors.lastname: Arias-de-la-Fuente
authors.forename: M A
authors.initials: MA
authors.lastname: Gómez-Ferrería
authors.forename: B
authors.initials: B
authors.lastname: Granadino
authors.forename: J
authors.initials: J
authors.lastname: Rey-Campos
mesh_terms: D017398:Alternative Splicing / Q000235:genetics; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D051858:Forkhead Transcription Factors; D020869:Gene Expression Profiling; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009928:Organ Specificity; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation
chemical_list: D004268:DNA-Binding Proteins; C408469:FOXJ2 protein, human; D051858:Forkhead Transcription Factors; D020033:Protein Isoforms; D012333:RNA, Messenger; D015534:Trans-Activators