Abstract
A Ca2+-insensitive myosin light chain kinase was prepared and used in experiments with skinned gizzard fibers. In the absence of Ca2+, this kinase activated isometric force development. The force development was associated with phosphorylation of the 20,000-dalton myosin light chains and addition of Ca2+ did not activate the fibers further. Pretreatment of the fibers with Ca2+-insensitive myosin light chain kinase and adenosine 5'-O-(3-thiotriphosphate) in the absence of Ca2+ caused thiophosphorylation of the light chains and, on the addition of ATP, an activation of isometric tension was observed. The subsequent addition of Ca2+ did not increase force development. A comparison of Ca2+-activated tension in the skinned gizzard muscle fibers with Ca2+-insensitive myosin light chain kinase-activated tension suggests that the phosphorylation of the myosin light chains is the dominant factor in the development of tension in smooth muscle.
Original language | English (US) |
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Pages (from-to) | 5987-5990 |
Number of pages | 4 |
Journal | Journal of Biological Chemistry |
Volume | 257 |
Issue number | 11 |
State | Published - Jun 10 1982 |
Externally published | Yes |
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology