Structure and complete nucleotide sequence of the chicken alpha-smooth muscle (aortic) actin gene. An actin gene which produces multiple messenger RNAs.

The alpha-smooth muscle (aortic) actin gene is a distinct member of the actin multigene family which is expressed in vascular smooth muscle cells. We have determined the complete nucleotide sequence of 11 kilobase pairs of genomic DNA encoding the chicken alpha-smooth muscle actin gene. This single copy gene specifies a protein identical in sequence to the major alpha-actin from bovine aorta. The protein-coding sequences are interrupted by seven introns which are at codons specifying amino acid residues 41/42, 84/85, 121/122, 150, 204, 267, and 327/328. An eighth intron was found in the mRNA 5' untranslated region. The 5' flanking sequences contain elements which are conserved in other chicken muscle actin genes. Additional sequences at the 5' end of the gene may be conserved in at least one human actin gene. We have identified at least four messenger RNAs ranging in size from approximately 1370 to 2700 nucleotides (excluding poly(A) tails) which are transcribed from the alpha-smooth muscle actin gene. These RNAs differ in the length of their 3' untranslated regions, probably as a result of the utilization of alternative polyadenylation signals. This is the first report of an actin gene with multiple mRNA transcripts.