title: A multiplicity of CCAAT box-binding proteins.
abstract: NF-Y is a sequence-specific DNA-binding protein that recognizes the Y box, a promoter element common to all major histocompatibility complex class II genes. Since the 14-base Y element harbors a CCAAT box in reverse, we were prompted to ask whether NF-Y is actually a CCAAT box-binding protein and whether it is related to the previously described CCAAT-binding factors CBP and CTF/NF-I. Data from gel retardation, methylation interference, saturation mutagenesis, and cross-competition experiments establish definitively that NF-Y is an entirely distinct CCAAT box-binding entity. Moreover, these experiments have uncovered a fourth CCAAT-binding protein, NF-Y(star) that interacts with the thymidine kinase promoter. Clearly, then, there exists a multiplicity of factors that recognize CCAAT sequences; it now becomes imperative to understand the functional significance of this multiplicity.
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000145:classification / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D005786:Gene Expression Regulation; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D051379:Mice; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000145:classification / Q000302:isolation & purification*
chemical_list: D004268:DNA-Binding Proteins; D000949:Histocompatibility Antigens Class II; C024138:I-E-antigen; D014157:Transcription Factors