The p48 DNA-binding subunit of transcription factor PTF1 is a new exocrine pancreas-specific basic helix-loop-helix protein.
We report the isolation of cDNA for the p48 DNA-binding subunit of the heterooligomeric transcription factor PTF1. A sequence analysis of the cDNA demonstrates that p48 is a new member of the family of basic helix-loop-helix (bHLH) transcription factors. The p48 bHLH domain shows striking amino acid sequence similarity with the bHLH domain of proteins that act as developmental regulators, including the twist gene product, myogenic factors and proteins involved in hematopoietic differentiation. We show that reduced p48 synthesis correlates with a diminished expression of genes encoding exocrine pancreas-specific functions. The synthesis of p48 mRNAs, and therefore also the protein, is restricted to cells of the exocrine pancreas in the adult and to the pancreatic primordium in the embryo. Thus the pancreas-specific DNA-binding activity of PTF1 originates from the synthesis of at least one cell-specific component rather than from a cell-specific assembly of more widely distributed proteins.
Krapp
A
A
Swiss Institute for Experimental Cancer Research (ISREC), Epalinges/Lausanne, Switzerland.
Knöfler
M
M
Frutiger
S
S
Hughes
G J
GJ
Hagenbüchle
O
O
Wellauer
P K
PK
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry; D018507:Gene Expression Regulation, Developmental; D018257:Helix-Loop-Helix Motifs; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D005810:Multigene Family; D009928:Organ Specificity; D010179:Pancreas / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D051792:Basic Helix-Loop-Helix Proteins; D004247:DNA; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; C062602:transcription factor PTF1