Integrity of FOS B leucine zipper is essential for its interaction with JUN proteins.
fos B encodes a nuclear protein with 70% homology to c-fos, whose expression is transiently induced during the G0/G1 transition. Immunoprecipitation studies demonstrated that FOS B protein forms a complex in vitro with c-JUN, JUN B, and JUN D. We have mutated some of the leucines of the 'leucine zipper' present in the FOS B protein and determined their effect in the interaction with JUN proteins and their binding to an AP-1 containing sequence. The exchange of either leucine 1, 3, or 5 of the leucine repeat of FOS B to a proline dramatically inhibits its association with JUN proteins. However, a more conserved substitution to isoleucine has only a 50% inhibition. These results demonstrate that any major alteration in the alpha-helical structure of the 'leucine zipper' completely inhibits the interaction of FOS B with any of the three JUN proteins.
Ryseck
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Squibb Institute for Medical Research, Department of Molecular Biology, Princeton, New Jersey 08543-4000.
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D000595:Amino Acid Sequence; D001483:Base Sequence; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000502:physiology*; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000502:physiology* / Q000648:ultrastructure; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000502:physiology* / Q000648:ultrastructure; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012045:Regulatory Sequences, Nucleic Acid; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000502:physiology* / Q000648:ultrastructure
D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D014157:Transcription Factors