Abstract
Skinned tail and leg muscle fibers of the limulus were used to study the mechanism of Ca2+ regulation of contraction. Although a Ca2+-sensitive 31,000 dalton protein phosphorylation could be observed in the presence of [γ-32P] ATP no such phosphorylation occurred in the presence of [γ-32P] ITP. Ca2+-activated tension occurred equally as well in ATP and ITP. For this reason we eliminated the possibility that a Ca2+-sensitive myosin light chain kinase/phosphatase system is the mechanism responsible for the Ca2+-activated tension. Other agents known to affect a myosin light chain kinase/phosphatase system showed negative results (ATPγS, trifluoperazine, catalytic subunit of the cyclic adenosine 3′,5′-monophosphate dependent protein kinase and calmodulin). Troponin I reversibly inhibits Ca2+-activated tension. These results are consistent with thin filament regulation being responsible for Ca2+-activated tension in skinned fibers.
Original language | English (US) |
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Pages (from-to) | 121-124 |
Number of pages | 4 |
Journal | Pflügers Archiv European Journal of Physiology |
Volume | 392 |
Issue number | 2 |
DOIs | |
State | Published - Dec 1 1981 |
Externally published | Yes |
Keywords
- Ca
- ITP
- Limulus
- Myosin light chain
- Phosphorylation
- Skinned fibers
ASJC Scopus subject areas
- Physiology