Structure of 3'-downstream segment of the human smooth muscle (aortic-type) alpha-actin-encoding gene and isolation of the specific DNA probe.

We isolated the 3'-downstream part of the human aortic smooth muscle alpha-actin (SM alpha A)-encoding gene and determined the nucleotide sequence, including the ninth (last) exon and 3'-untranslated (UT) region. From the comparison of the human 3'-UT region with rat and chicken 3'-UT regions, its homology is lower than those in 3'-UT regions of other actin isoforms such as cardiac alpha-actin and cytoskeletal beta-actin. Therefore, by using the 3'-UT region of the human SM alpha A gene as an actin isoform-specific probe, this gene was detected as a single copy only in the human genome, which expressed the 1.7-kb RNA transcript in an aortic tissue-specific manner.