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A novel 16-kilodalton cellular protein physically interacts with and antagonizes the functional activity of c-myc promoter-binding protein 1.

We initially identified c-myc promoter-binding protein 1 (MBP-1) from a human cervical carcinoma cell expression library which negatively regulates c-myc promoter activity. A recent study demonstrated that MBP-1 acts as a general transcriptional repressor (A. K. Ghosh, R. Steele, and R. B. Ray, Mol. Cell. Biol. 19:2880-2886, 1999). In order to identify the cellular protein(s) interacting with MBP-1 for transcriptional regulation, a HeLa cell cDNA expression library was screened using a yeast two-hybrid system. An MBP-1-interacting cDNA encoding a polypeptide of 140 amino acid residues with an approximate molecular mass of 16 kDa was identified and named MBP-1 interacting protein-2A (MIP-2A). MIP-2A has a sequence similarity with an unknown mRNA and SEDL. Mutations in the SEDL gene, located at human chromosome Xp22, has recently been implicated with an X-linked genetic disease, although the function of SEDL gene product was not determined (A. K. Gedeon et al., Nat. Genet. 22:400-404, 1999). However, our results suggested the localization of MIP-2A at human chromosome 19. The specificity of interaction between MBP-1 and MIP-2A was verified by an in vitro glutathione S-transferase pulldown experiment, a mammalian two-hybrid analysis, and in vivo coimmunoprecipitation assays. Further analysis revealed that the amino-terminal domain of MBP-1 (amino acids 1 to 95) interacts with MIP-2A. Immunofluorescent staining suggested colocalization of MIP-2A and MBP-1 primarily in the perinuclear membrane of cells. Functional analysis demonstrated that MIP-2A relieves MBP-1 mediated transcriptional repression on c-myc promoter. Additionally, MIP-2A antagonizes cell growth regulatory role of MBP-1. Taken together, these results suggest the functional interaction of MIP-2A and MBP-1 in cell growth regulation.

Pubmed ID: 11134351


  • Ghosh AK
  • Majumder M
  • Steele R
  • White RA
  • Ray RB


Molecular and cellular biology

Publication Data

January 2, 2001

Associated Grants

  • Agency: NCI NIH HHS, Id: CA52799

Mesh Terms

  • 3T3 Cells
  • Animals
  • Binding Sites
  • Cell Death
  • Cell Division
  • Chromosomes, Human, Pair 19
  • DNA-Binding Proteins
  • Fluorescent Antibody Technique
  • Gene Expression Regulation
  • Genes, Reporter
  • Genes, myc
  • HeLa Cells
  • Humans
  • Membrane Transport Proteins
  • Mice
  • Molecular Sequence Data
  • Molecular Weight
  • Neoplasm Proteins
  • Phosphopyruvate Hydratase
  • Physical Chromosome Mapping
  • Promoter Regions, Genetic
  • Protein Binding
  • Protein Structure, Tertiary
  • Repressor Proteins
  • Transcription Factors
  • Transfection
  • Tumor Markers, Biological
  • Tumor Suppressor Proteins
  • Two-Hybrid System Techniques