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The first exon of the c‐myc proto‐oncogene contains a novel positive control element.
Author(s) -
Yang J.Q.,
Remmers E.F.,
Marcu K.B.
Publication year - 1986
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1986.tb04682.x
Subject(s) - exon , biology , chloramphenicol acetyltransferase , promoter , transcription (linguistics) , enhancer , microbiology and biotechnology , gene , gene expression , genetics , linguistics , philosophy
We have identified a positive modulator within the c‐myc first exon downstream of the gene's transcription initiation sites, P1 and P2. We introduced myc‐CAT (chloramphenicol acetyltransferase) hybrid genes into three cell lines (BJAB, COS and HeLa) and measured their expression by either CAT enzymatic activity, S1 nuclease protection or by a nuclear ‘run‐on’ transcription assay. Removal of 46 bp from the 3′ end of the first exon results in a decrease of myc‐CAT expression and P2 activity. A 438‐bp exon 1 segment, lacking the normal myc promoters, efficiently drives the expression of SV40 early promoters. We find that this first exon segment efficiently functions as a positive modulator only in its sense orientation, 3′ of a nearby promoter. The positive effects of the myc first exon and the SV40 enhancer are complementary.