The bromodomain: a conserved sequence found in human, Drosophila and yeast proteins

摘要: Identification of conserved domains or motifs in proteins may aid the localization and analysis important structural functional regions. We report here a protein sequence motif, called bromodomain (1), that has been found six genes from humans (CCG1 RING3), Drosophila (fsh brm), yeast (SPT7 SNF2). The fsh brm are required maternally for proper expression certain homeotic (1,2). SPT7 SNF2 Saccharomyces cerevisiae encode transcriptional activators (3,4). have extensive homology (1). It is not clear whether two human involved processes. CCG1 DNA-binding complements temperature sensitive mutations cause cell cycle arrest Gl (5). RING3 gene newly identified unknown function, mapping to class II region major histocompatibility locus, substantial (6). Each these one copies 61 —63 amino acid (Figure 1). identity highest (~ 80%) between corresponding repeats. More typically, any show 25-40% identity, with 50-60% repeats within same protein. There seven invariant residues, four which aromatic acids, numerous conservative substitutions. location motif(s) individual variable, be present tandem separated by sequences unrelated motif. Secondary structure prediction methods were applied revealed strongly predicted amphipathic helices followed reverse turns. Four residues located turns, other three among highly proline at N terminus. significance unknown, experiments indicate it dispensable some cases (6; P.Tan F.W., unpublished data). However, widespread conservation suggests aspects function. speculate hydrophobic surfaces could serve as sites intramolecular intermolecular protein-protein interaction. Such interactions influence assembly activity multicomponent complexes transcription activation cellular