Major Egr3 isoforms are generated via alternate translation start sites and differ in their abilities to activate transcription.
In previous studies, we detected a major, unidentified Egr response element (ERE) binding complex in brain extracts. We now report that this complex contains a truncated isoform of Egr3 generated by use of an alternate translation start site at methionine 106. Furthermore, the ERE binding complex previously thought to contain full-length Egr3 includes several isoforms generated by initiation at other internal methionines. Full-length and truncated (missing residues 1 to 105) Egr3 isoforms differ in the ability to stimulate transcription directed by a tandem repeat of two EREs but not by a single ERE. Taken together, our results indicate that alternative translation start sites are used to generate Egr3 isoforms with distinct transcriptional properties.
O'Donovan
K J
KJ
Departments of Neuroscience and Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Baraban
J M
JM
D017398:Alternative Splicing; D000818:Animals; D001921:Brain / Q000378:metabolism; D002460:Cell Line; D018387:Codon, Initiator; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D051776:Early Growth Response Protein 3; D015870:Gene Expression; D006801:Humans; D008297:Male; D008715:Methionine; D051379:Mice; D018345:Mice, Knockout; D016296:Mutagenesis; D014176:Protein Biosynthesis; D020033:Protein Isoforms; D051381:Rats; D017207:Rats, Sprague-Dawley; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D018387:Codon, Initiator; D004268:DNA-Binding Proteins; C497369:Egr3 protein, mouse; C497370:Egr3 protein, rat; D020033:Protein Isoforms; D014157:Transcription Factors; D051776:Early Growth Response Protein 3; D008715:Methionine