TPM1 has 10 named isoforms with tissue-specific expression patterns.
| Isoform | UniProt ID | Synonym | Tissue | Key Feature |
|---|---|---|---|---|
| Isoform 1 | P09493-1 | TPM1alpha, Skeletal | Skeletal muscle | Adult striated muscle |
| Isoform 2 | P09493-2 | Smooth muscle | Smooth muscle | Vascular, visceral |
| Isoform 3 | P09493-3 | TM3, Fibroblast | Non-muscle cells | Cytoskeletal function |
| Isoform 6 | P09493-6 | TPM1kappa | Cardiac | Cardiac-specific |
Striated muscle isoforms (1, 6):
- Regulate actin-myosin interaction in sarcomeres
- Essential for muscle contraction
- Mutations cause cardiomyopathy
Smooth muscle isoform (2):
- Different N-terminal sequence
- Expressed in blood vessels, uterus, GI tract
- Regulates smooth muscle contraction
Non-muscle isoforms (3, etc.):
- Cytoskeletal organization
- Cell motility
- Different actin binding properties
Cardiomyopathy mutations:
- CMH3: Familial hypertrophic cardiomyopathy
- CMD1Y: Dilated cardiomyopathy
- Mutations affect sarcomere function
UniProt tissue specificity:
"Isoform 1 is expressed in adult and fetal skeletal muscle and cardiac tissues, with higher expression levels in the cardiac tissues. Isoform 10 is expressed in adult and fetal cardiac tissues, but not in skeletal muscle."