High impact information on MYOM1

• Furthermore, similar to titin, myomesin is a molecular spring with complex visco-elastic properties that can be modified by alternative splicing [1].
• These have shown that antiparallel myomesin dimers might link the thick filaments in the M-band, a role analogous to that of alpha-actinin in the Z-disc [1].
• The M-band molecular structure has been clarified recently by biochemical and biophysical approaches that focused on the properties of the prominent M-band component myomesin [1].
• This interaction is regulated by phosphorylation of Ser482 in the linker between myomesin domains My4 and My5 [2].
• The tissue specificity of chicken 165,000 M-protein, tentatively names "myomesin", a tightly bound component of the M-line region of adult skeletal and heart myofibrils, was investigated by immunological techniques [3].

Biological context of MYOM1

• We suggest that similarly to titin, myomesin is a molecular spring, whose elasticity is modulated by alternative splicing [4].
• No significant amounts of myomesin were, however, found in cells prevented from undergoing normal myogenesis by 5'-bromodeoxyuridine [3].
• Our data suggest that myomesin can form antiparallel dimers via a binding site residing in its C-terminal domain 13 [5].
• Transfection of these cells with truncated myomesin fragments showed that a specific part of the myomesin molecule, known to contain a titin-binding site, binds to MLSs, whereas other parts do not [6].
• Expression of sarcomeric myosin heavy chain (sMyHC) is observed in a small minority of cells, while other sarcomeric proteins, such as nebulin, myosin binding protein C (MyBP-C), myomesin and M-protein are not expressed at all [6].

Anatomical context of MYOM1

• These complex visco-elastic properties of myomesin might be crucial for the stability of the sarcomere [4].
• We report a method for isolating homogeneous myomesin from mammalian skeletal muscle [7].
• The results indicate that myomesin (a) is a myofibrillar protein specific for cross-striated muscle, (b) represents a highly specific marker for cross-striated muscle cell differentiation and (c) might play an important role in myofibril assembly and/or maintenance [3].
• Only skeletal and heart muscle cells, but not smooth muscle or fibroblast cells, showed the presence of myomesin [3].
• No myomesin could however, be detected in smooth muscle or any other tissue tested [3].

Associations of MYOM1 with chemical compounds

• Muscle-type creatine kinase interacts with central domains of the M-band proteins myomesin and M-protein [8].
• Protein sequence analysis indicated that a 45-residue sequence in the NH2-terminal C0 domain of cMyBP-C exhibits a consistent homology (sequence similarity score of 42 %) with a segment of the NH2-terminal domain of myomesin, another myosin-binding protein [9].

Regulatory relationships of MYOM1

• Myomesin phosphorylation at this site by cAMP-dependent kinase and similar or identical activities in muscle extracts block the association with titin [2].

Other interactions of MYOM1

• We propose that the spatial coordination of this assembly is regulated by specific interactions of myosin filaments, the M band protein myomesin and the large carboxy-terminal region of titin [2].
• At pH 6.8, the dissociation constants for the myomesin/MM-CK and the M-protein/MM-CK binding were in the range of 50-100 nM and around 1 microM, respectively [8].
• In contrast, the contractile myofilaments and the proteins of the sarcomeric skeleton including titin, alpha-actinin, and myomesin are significantly decreased [10].
• Desmin and myomesin showed an intermediate response; changes began at 30 to 40 minutes, and disruption was complete at 90 to 120 minutes [11].
• In addition, specific proteins found in muscle tissue such as the troponins, tropomyosin, alpha- and beta-actinin, desmin, vimentin, myomesin, and creatine kinase are described [12].

Analytical, diagnostic and therapeutic context of MYOM1

• Here we use atomic force microscopy (AFM), transmission electron microscopy (TEM) and circular dichroism (CD) spectroscopy for the biophysical characterization of myomesin [4].
• Electron microscopy of myomesin revealed short flexible rods with a molecular length of about 50 nm [7].
• When the occurrence and the distribution of myomesin during differentiation of breast muscle cells in culture were studied by the indirect immunofluorescence technique, this protein was first detected in postmitotic, nonproliferating myoblasts in a regular pattern of fluorescent cross-striations [3].
• Here, in order to facilitate a better understanding of the physiological, and possibly pathological, functions of myomesin proteins, we explore the mechanical stability, elasticity and force-driven structural changes of human myomesin's sub-molecular segments using single-molecule force spectroscopy and protein engineering [13].
• By immunocytochemistry, myomesin protein is absent from adult EOM sarcomeres [14].

References