title: Distribution and characterization of helix-loop-helix enhancer-binding proteins from pancreatic beta cells and lymphocytes.
abstract: Transcription of a number of mammalian genes is controlled in part by closely-related DNA elements sharing a CAxxTG consensus sequence (E boxes). In this report, we survey cell extracts from a variety of mammalian cell lineages for ability to bind to the E box denoted IEB1/kappa E1, which plays an important role in expression of both insulin and immunoglobulin kappa genes. Insulin enhancer factor 1 (IEF1), a binding activity previously identified in beta cells, was also present in pituitary endocrine cells but absent in 7 other mammalian cell lines tested. A distinct binding activity, lymphoid enhancer factor 1 (LEF1), was observed in several lymphoid cell lines, but was absent from all nonlymphoid cells tested. IEF1 and LEF1 were distinct according to electrophoretic mobility, and DNA binding specificity. As previously reported, both beta cell and lymphoid cell factors are recognized by antibodies to helix-loop-helix (HLH) proteins, indicating that they may contain functional helix-loop-helix dimerization domains. To directly demonstrate this, we showed that the binding factors are able to interact in vitro with the HLH domain of a characterized HLH protein. These results support the notion that HLH proteins play a key role in cell-specific transcriptional regulation in cells from endocrine and lymphocyte lineages.
authors.affiliation: Department of Biochemistry, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Aronheim
authors.forename: H
authors.initials: H
authors.lastname: Ohlsson
authors.forename: C W
authors.initials: CW
authors.lastname: Park
authors.forename: T
authors.initials: T
authors.lastname: Edlund
authors.forename: M D
authors.initials: MD
authors.lastname: Walker
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D002460:Cell Line; D004247:DNA; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D018398:Homeodomain Proteins; D007515:Islets of Langerhans / Q000378:metabolism*; D060850:LIM-Homeodomain Proteins; D008214:Lymphocytes / Q000378:metabolism*; D051821:Lymphoid Enhancer-Binding Factor 1; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins / Q000378:metabolism; D009928:Organ Specificity; D011487:Protein Conformation; D051381:Rats; D014157:Transcription Factors
chemical_list: D000906:Antibodies; D051792:Basic Helix-Loop-Helix Proteins; D004247:DNA; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D060850:LIM-Homeodomain Proteins; D051821:Lymphoid Enhancer-Binding Factor 1; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; C064943:IEBP1 protein, rat; C497574:Lef1 protein, mouse; C497575:Lef1 protein, rat; C063843:insulin gene enhancer binding protein Isl-1