Myosin as cofactor and substrate in fibrinolysis.
Myosin accelerates plasminogen activation by tissue-type plasminogen activator (tPA), and is degraded extensively by plasmin. Myosin binds both tPA and plasminogen, and enhances activation of des1-77-plasminogen by tPA but not by urokinase-type plasminogen activator (uPA). Myosin decreases K(M) and increases k(cat) for des1-77-plasminogen activation by tPA, to yield catalytic efficiencies in excess of 8000 M-1 s-1. The effect of myosin is attributed to its C-terminal portion, the myosin rod. With a K(M) of 3 microM, myosin is a high-affinity substrate for plasmin. The findings indicate that myosin is a cofactor for plasminogen activation and a substrate for plasmin.
Machovich
R
R
Section of Hematology Research, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
Ajtai
K
K
Kolev
K
K
Owen
W G
WG
D000818:Animals; D004789:Enzyme Activation; D005341:Fibrinolysin / Q000378:metabolism*; D005342:Fibrinolysis / Q000502:physiology*; D006801:Humans; D009218:Myosins / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D010958:Plasminogen / Q000378:metabolism*; D010959:Tissue Plasminogen Activator / Q000378:metabolism*; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism
D010446:Peptide Fragments; D010958:Plasminogen; D010959:Tissue Plasminogen Activator; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator; D009218:Myosins