Recent Progress in the Association of TPM1 in Cardiogenesis, Myofibrillogenesis, and Heart Diseases

Tropomyosins, a family of actin-binding, coiled-coil dimeric proteins, are found in all eukaryotic organisms from yeast to man. Tropomyosin (TPM) is best known for its role in muscle contraction. It is a component of thin filaments in muscle cells and also a component of microfilaments in non-muscle cells The protein was discovered in the 1940s as a component of the actin filaments of striated muscle [1]. To date, there are more than 40 TPM isoforms known in humans as well asinother vertebrates. These isoforms are encoded in vertebrates by four TPM genes (TPM1, TPM2, TPM3, and TPM4) [2-4] except infish where six TPM genes are present [5]. The TPM1 gene was previously known to produce nine isoforms only one of which, TPM1α is specific for striated muscle (i.e., termed asarcomeric isoform). In 2004 we reported a second sarcomeric isoform called TPM1κ (or Tpm 1.2) (Figure1) [6,7]. Since then, we have reported 4 more high molecular weight isoforms from humans, which are not sarcomeric isoforms (Figure 1 as shown in the box).