Formin-g muscle cytoarchitecture.

Striated muscle cells display an extremely regular assembly of their actin cytoskeleton that contributes to the contractile elements, the myofibrils. How this assembly is initiated and how these structures are maintained is still unclear. We have recently shown that striated muscle expresses a specific isoform of the formin protein family member FHOD3, which is characterised by the presence of a CK2 phosphorylation site at the C-terminal end of the formin homology domain 2 (FH2).

Structural insight into M-band assembly and mechanics from the titin-obscurin-like-1 complex.

In the sarcomeric M-band, the giant ruler proteins titin and obscurin, its small homologue obscurin-like-1 (obsl1), and the myosin cross-linking protein myomesin form a ternary complex that is crucial for the function of the M-band as a mechanical link. Mutations in the last titin immunoglobulin (Ig) domain M10, which interacts with the N-terminal Ig-domains of obscurin and obsl1, lead to hereditary muscle diseases. The M10 domain is unusual not only in that it is a frequent target of disease-linked mutations, but also in that it is the only currently known muscle Ig-domain that interacts with two ligands--obscurin and obsl1--in different sarcomeric subregions.