H. Honda et al., DECORATING ACTIN-FILAMENTS WITH TROPONIN T-I COMPLEXES AND ACCELERATION OF THEIR SLIDING MOVEMENT ON MYOSIN MOLECULES, Biochimica et biophysica acta. Protein structure and molecular enzymology, 1251(1), 1995, pp. 43-47
Actin filaments, when partially decorated with troponin T-I complexes,
can slide faster on myosin heads than those with no decoration. Purif
ied troponin T-I complexes bind to actins, and inhibit the actin activ
ated myosin adenosine 5'-triphosphatase activity completely when the m
olar ratio of troponin T-I complex to actin is increased to 1 to 1. Th
ose actin filaments decorated with troponin T-I complexes up to 20 to
50% of their molar ratio exhibit enhancement of the velocity of slidin
g on myosins up to 20% compared to those without such decoration. As t
he molar ratio of decoration further increases, the sliding velocity d
ecreases. These results are consistent with the observation that even
if some of actin monomers do not participate in the ATPase activity di
rectly, they can interact with myosin heads and take part in the slidi
ng movement.