The sarcomeric cytoskeleton: who picks up the strain?

In striated muscle sarcomeres, the contractile actin and myosin filaments are organised by a subset of specialised cytoskeletal proteins, the sarcomeric cytoskeleton. They include a-actinin, myomesin, and the giant proteins titin, obscurin and nebulin, which combine architectural, mechanical and signalling functions. Mechanics and signalling in the sarcomere appear tightly interdependent, but the exact contributions of the various sarcomeric cytoskeleton proteins to strain handling or signalling are only just emerging. General mechanisms of cytoskeletal mechanics and signalling may be gleaned from the sarcomere as a specialised actomyosin system. Recent work has led to insight into the interactions, structure, and mechanical stability of sarcomeric protein complexes that fulfil both structural and signalling roles.