A pancreatic exocrine cell factor and AP4 bind overlapping sites in the amylase 2A enhancer.
A factor found in pancreatic exocrine cell lines and pancreatic nuclei binds selectively to the alpha-amylase 2A transcriptional enhancer. Pancreatic exocrine cell extracts protect asymmetrically an unusually large, 35 base pair region from DNase I digestion in vitro, suggesting the involvement of a multimeric DNA binding complex. We show that this region of the enhancer contains a major affinity recognition sequence for the HeLa transcription factor AP4. A 4 base pair mutation in the enhancer sequence shown previously to abolish activity in vivo [Boulet, A. M., Erwin, C. R., & Rutter, W. J. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 3599-3603] abolishes AP4 binding in vitro and weakens but does not eliminate the binding of adjacent enhancer factors. Further, sequences similar to the AP4 binding site are found within a consensus sequence of most pancreatic exocrine genes (Boulet et al., 1986). We have identified three AP4 binding sites in the pancreatic elastase gene: one occurs in the consensus sequence of the enhancer. Thus, protein(s) with the binding selectivity of AP4 may play a role in the expression of the pancreatic exocrine gene family.
Fodor
E
E
Department of Biochemistry and Biophysics, University of California, San Francisco 94143.
Weinrich
S L
SL
Meister
A
A
Mermod
N
N
Rutter
W J
WJ
D000681:Amylases / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D006224:Cricetinae; D004268:DNA-Binding Proteins / Q000235:genetics*; D004285:Dogs; D004742:Enhancer Elements, Genetic; D005807:Genes, Overlapping; D007340:Insulinoma / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010179:Pancreas / Q000201:enzymology / Q000378:metabolism*; D051381:Rats; D013539:Simian virus 40 / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics*
D004268:DNA-Binding Proteins; D014157:Transcription Factors; C055473:enhancer-binding protein AP-4; D000681:Amylases