PNAS Plus Significance Statements

2015 Proceedings of the National Academy of Sciences of the United States of America  
All animals have the ability to move. In most animals, striated muscles move the body and smooth muscles the internal organs. In both muscles, contraction results from interaction between myosin and actin filaments. Based on vertebrate studies, smooth and striated muscles are thought to have different protein components and filament structures. We have studied muscle ultrastructure in the parasite Schistosoma mansoni, where we find that this view is not supported. This invertebrate possesses
more » ... ebrate possesses only smooth muscles, yet its myosin sequence and filament structure are identical to those of striated muscle, while its actin filaments are smooth muscle-like. Such "hybrid" muscles may be common in other invertebrates. This finding challenges the paradigm that smooth and striated muscles always have different components. (See pp. E5660-E5668.)
doi:10.1073/pnas.ss11242 fatcat:y5zkprq5tbffzisipm56k4p45e