1987/04/01 by Nelson Ruiz‐Opazo, B Nadal-Ginard · 4 citations
Medicine · Biochemistry, Genetics and Molecular Biology · Mathematics · #Cardiomyopathy and Myosin Studies #Muscle Physiology and Disorders #RNA Research and Splicing #Tropomyosin #Gene isoform #Exon #Alternative splicing #RNA splicing #Gene #Isotype #Alpha (finance) #Biology #Cell biology #Genetics #Myosin #Antibody #Mathematics
paper · doi:10.1016/s0021-9258(18)61260-8
openalex publication_date 1987/04/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We have previously isolated and characterized cloned complementary DNAs (cDNAs) for striated and smooth muscle alpha-tropomyosin. The sequences of these cDNA clones suggested that these two isoforms were encoded by the same gene. Here, we have determined the complete structure of the alpha-tropomyosin (alpha-TM) gene, establishing that a single gene, with a sequence complexity of 28 kilobase pairs, is split into 12 exons and produces the smooth and striated muscle alpha-TM mRNA isoforms by alternative splicing of a minimum of five exchangeable isotype-specific exons. The elucidation of the intron/exon organization of alpha-TM suggests that this gene evolved from an ancestral gene encoding a 21-aa protein that might represent the primordial actin binding domain. Sequence comparison between the pairs of exons coding for the "isotype switch regions" and among the corresponding regions of tropomyosin genes in a variety of species ranging from insects to mammals, suggests that the alternatively spliced exons are very old and might have arisen before the radiation of the arthropods, more than 600 million years ago. Additionally, the examination of the intronic sequences has uncovered potential alternative intramolecular secondary structures (hairpin-loop structures) which might be involved in the tissue-specific expression of the duplicated and mutually exclusive alpha-TM isotype-specific exons.