Do thin filaments of smooth muscle contain calponin?
1990; Wiley; Volume: 268; Issue: 1 Linguagem: Inglês
10.1016/0014-5793(90)80999-y
ISSN1873-3468
AutoresWataru Nishida, Masahiro Abe, Katsuhito Takahashi, Kunio Hiwada,
Tópico(s)Lubricants and Their Additives
ResumoA new method for the preparation of smooth muscle thin filaments which include calponin was established. We found that calponin readily separated from thin filaments in the presence of 10 mM ATP. By preventing thin filament extract from exposing to ATP, we obtained thin filaments which contained actin, tropomyosin, caldesmon and calponin in molar ratios of 7:0.9:0.6:0.7. We studied myosin Mg‐ATPase activity by using the thin filaments in comparison with classical thin filaments prepared by the method of Marston and Smith, which contained the same amounts of caldesmon and tropomyosin as our thin filaments but lost almost all calponin. The presence of calponin reduced the V max value for thin filament‐activated myosin Mg‐ATPase activity by 33% without a significant change in K m value. These findings suggest that calponin inhibits myosin Mg‐ATPase activity by modulation of a kinetic step as an integral component of smooth muscle thin filaments.
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