Molecular characterization of the rat insulin enhancer-binding complex 3b2. Cloning of a binding factor with putative helicase motifs.
Cell-specific expression of the rat insulin II gene is in part mediated through an element located in the 5'-flanking region. The element, termed RIPE3b (-126 to -101), confers beta-cell-specific expression in conjunction with an adjacent element RIPE3a (-110 to -86). Here we report the characterization of one of the RIPE3b-binding complexes, 3b2. UV cross-linking analysis demonstrated that it is composed of at least three polypeptides: p58, p62, and p110. Furthermore, a cDNA was isolated via expression screening for binding to RIPE3b. Sequence analysis reveals that the encoded protein, designated Rip-1, possessed putative helicase motifs and a potential transcription activation domain. Overexpression of Rip-1 in cells greatly enhances the 3b2 binding complex, suggesting that Rip-1 is involved in the binding of 3b2.
Shieh
S Y
SY
Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
Stellrecht
C M
CM
Tsai
M J
MJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D006224:Cricetinae; D004265:DNA Helicases / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D005786:Gene Expression Regulation; D015723:Gene Library; D006801:Humans; D007328:Insulin / Q000235:genetics*; D007515:Islets of Langerhans / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors; D014162:Transfection
D004268:DNA-Binding Proteins; C489892:IGHMBP2 protein, human; C081225:Ighmbp2 protein, mouse; D007328:Insulin; D011994:Recombinant Proteins; D014157:Transcription Factors; D004265:DNA Helicases