Identification and expression analysis of alternative transcripts of the mouse GA-binding protein (Gabp) subunits α and β1

The erythroblast transformation specific (ETS) transcription factor GA-binding protein (Gabp) is widely expressed and acts on a diverse range of target genes, including nuclear-encoded mitochondrial proteins and neuromuscular-specific genes. The GABPα subunit contains an ETS DNA binding domain and the β subunit contains a nuclear localization signal (NLS) and transactivation domain. Here, we show coincident expression of Gabpα and β1 throughout mouse embryogenesis, consistent with the gene products functioning in a complex. We have also identified 2 alternatively spliced, tissue-specific exons 1 (5′ untranslated regions) of mouse Gabpα and 4 alternative 3′ polyadenylation signals that, in combination, result in 12 transcripts for Gabpα. These alternative transcripts are suggested to have altered stability, subcellular localization and/or translation efficiency. Further, we identified nine differentially expressed splice variants of mouse Gabpβ1 that encode β protein forms lacking functional domains, suggesting a dominant negative function. Together, alternative transcripts of Gabpα and β1 provide a mechanism for tissue-specific regulation of Gabp activity.