Table 1.
Major myosin isoforms expressed in mammal muscle
| Gene | Protein | Functional properties | Expression pattern |
|---|---|---|---|
| MYH1 | MyHC-2X | Fast contracting | Multiple skeletal muscles, Type 2X fibers |
| MYH2 | MyHC-2A | Fast contracting | Multiple skeletal muscles, Type 2A fibers |
| MYH3 | MyHC-emb | Slow contracting87 | Developing and regenerating muscle |
| MYH4 | MyHC-2B | Fast contracting | Not in humans, multiple skeletal muscles, Type 2B fibers |
| MYH6 | MyHC-alpha | Intermediate speed88 | Cardiac and skeletal muscle of the jaws |
| MYH7 | MyHC-beta/slow | Slow contracting | Cardiac and slow skeletal muscles, Type 1 fibers |
| MYH8 | MyHC-neo | NA | Developing and regenerating muscle |
| MYH13 | MyHC-EO | Superfast cont.89 | Extraocular (EO) skeletal muscles |
| MYH14* | MyHC-slow/tonic | Slow contracting90 | Muscle spindles, Extraocular skeletal muscles |
| MYH15 | MyHC-15 | Slow contracting90 | Muscle spindles, Extraocular skeletal muscles |
| MYH16 | MyHC-M | Not in humans,° Translational Myolog it is evident Skeletal muscle of the jaws |
The table summarizes the nomenclature and expression pattern of the myosin heavy chain (MyHC) genes (MYH) and the corresponding sarcomeric protein product in mammals. The expression pattern in the striated muscles, as well as the functional properties in terms of contraction speed, are also reported. Hybrid fibers containing two MyHC