title: Mmip-2, a novel RING finger protein that interacts with mad members of the Myc oncoprotein network.
abstract: Mad proteins are basic-helix-loop-helix-leucine zipper (bHLH-ZIP)-containing members of the myc oncoprotein network. They interact with the bHLH-ZIP protein max, compete for the same DNA binding sites as myc-max heterodimers and down-regulate myc-responsive genes. Using the bHLH-ZIP domain of mad1 as a yeast two-hybrid 'bait', we identified Mmip-2, a novel RING finger protein that interacts with all mad members, but weakly or not at all with c-myc, max or unrelated bHLH or bZIP proteins. The mad1-Mmip-2 interaction is mediated by the ZIP domain in the former protein and by at least two regions in the latter which do not include the RING finger. Mmip-2 can disrupt max-mad DNA binding and can reverse the suppressive effects of mad proteins on c-myc-responsive target genes and on c-myc + ras-mediated focus formation in fibroblasts. Tagging with spectral variants of green fluorescent protein showed that Mmip-2 and mad proteins reside in separate cytoplasmic and nuclear compartments, respectively. When co-expressed, however, the proteins interact and translocate to the cellular compartment occupied by the more abundant protein. These observations suggest a novel way by which Mmip-2 can modulate the transcriptional activity of myc oncoproteins.
authors.affiliation: Section of Hematology/Oncology, Children's Hospital of Pittsburgh, University of Pittsburgh Cancer Institute, PA 15213, USA.
authors.forename: X Y
authors.initials: XY
authors.lastname: Yin
authors.forename: K
authors.initials: K
authors.lastname: Gupta
authors.forename: W P
authors.initials: WP
authors.lastname: Han
authors.forename: E S
authors.initials: ES
authors.lastname: Levitan
authors.forename: E V
authors.initials: EV
authors.lastname: Prochownik
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D003001:Cloning, Molecular; D018076:DNA, Complementary; D005656:Fungal Proteins / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D011233:Precipitin Tests; D011485:Protein Binding; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism*; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D005656:Fungal Proteins; C501382:MAD1 protein, S cerevisiae; C501384:MAD1L1 protein, human; C501385:Mad1l1 protein, mouse; D009687:Nuclear Proteins; D010750:Phosphoproteins; D016271:Proto-Oncogene Proteins c-myc; D012097:Repressor Proteins; C402374:Rnf17 protein, mouse; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors