Structural analysis of the mouse activin βC gene

Using a mouse activin βC cDNA probe, we have cloned over 38 kb of genomic DNA encompassing the mouse activin βC gene. Mouse activin βC is encoded by 2 exons separated by a large 12.1 kb intron. Exon 1 encodes the 17 amino acid signal peptide and 88 amino acids of the propeptide. Exon 2 encodes the remaining 130 amino acids of the propeptide and the entire 117 amino acid mature peptide. Unlike the activin βA and βB expression patterns, Northern blot analysis of adult mouse tissues shows that the activin βC mRNA is expressed only in the liver as a major species of ~2.1 kb. The liver-specific expression of activin βC suggests an important role of dimeric activin βC in normal liver function. These studies allow us to address the function of activin βC in mammalian development.