Abstract
Limited digestion of calmodulin (CaM)-dependent myosin light chain kinase from turkey gizzard with α-chymotrypsin in the presence of bound CaM generated an 80,000-dalton kinase fragment that was fully active in the absence of Ca2+. This kinase catalyzed specific Ca2+-independent phosphorylation of the 20,000-dalton light chain of myosin using isolated light chains, intact myosin, and actomyosin. Phosphorylation of myosin in the absence of Ca2+ allowed us to dissociate myosin phosphorylation from other potential Ca2+-dependent regulatory mechanisms, thus permitting an evaluation of the postulated central role of myosin phosphorylation in the regulation of smooth muscle contraction. Ca2+-independent myosin phosphorylation was found to cause loss of Ca2+ sensitivity of actin-activated myosin ATPase activity in a crude actomyosin preparation, and tension development in skinned smooth muscle fibers in the absence of Ca2+. Myosin phosphorylation is, therefore, the key event in actin activation of ATPase activity and initiation of contraction in skinned chicken gizzard fibers.
| Original language | English |
|---|---|
| Pages (from-to) | 45-50 |
| Number of pages | 6 |
| Journal | Federation Proceedings |
| Volume | 42 |
| Issue number | 1 |
| State | Published - Jan 1 1983 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Medicine(all)
Cite this
Gizzard Ca2+-independent myosin light chain kinase : Evidence in favor of the phosphorylation theory. / Walsh, M. P.; Bridenbaugh, R.; Kerrick, W. Glenn; Hartshorne, D. J.
In: Federation Proceedings, Vol. 42, No. 1, 01.01.1983, p. 45-50.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Gizzard Ca2+-independent myosin light chain kinase
T2 - Evidence in favor of the phosphorylation theory
AU - Walsh, M. P.
AU - Bridenbaugh, R.
AU - Kerrick, W. Glenn
AU - Hartshorne, D. J.
PY - 1983/1/1
Y1 - 1983/1/1
N2 - Limited digestion of calmodulin (CaM)-dependent myosin light chain kinase from turkey gizzard with α-chymotrypsin in the presence of bound CaM generated an 80,000-dalton kinase fragment that was fully active in the absence of Ca2+. This kinase catalyzed specific Ca2+-independent phosphorylation of the 20,000-dalton light chain of myosin using isolated light chains, intact myosin, and actomyosin. Phosphorylation of myosin in the absence of Ca2+ allowed us to dissociate myosin phosphorylation from other potential Ca2+-dependent regulatory mechanisms, thus permitting an evaluation of the postulated central role of myosin phosphorylation in the regulation of smooth muscle contraction. Ca2+-independent myosin phosphorylation was found to cause loss of Ca2+ sensitivity of actin-activated myosin ATPase activity in a crude actomyosin preparation, and tension development in skinned smooth muscle fibers in the absence of Ca2+. Myosin phosphorylation is, therefore, the key event in actin activation of ATPase activity and initiation of contraction in skinned chicken gizzard fibers.
AB - Limited digestion of calmodulin (CaM)-dependent myosin light chain kinase from turkey gizzard with α-chymotrypsin in the presence of bound CaM generated an 80,000-dalton kinase fragment that was fully active in the absence of Ca2+. This kinase catalyzed specific Ca2+-independent phosphorylation of the 20,000-dalton light chain of myosin using isolated light chains, intact myosin, and actomyosin. Phosphorylation of myosin in the absence of Ca2+ allowed us to dissociate myosin phosphorylation from other potential Ca2+-dependent regulatory mechanisms, thus permitting an evaluation of the postulated central role of myosin phosphorylation in the regulation of smooth muscle contraction. Ca2+-independent myosin phosphorylation was found to cause loss of Ca2+ sensitivity of actin-activated myosin ATPase activity in a crude actomyosin preparation, and tension development in skinned smooth muscle fibers in the absence of Ca2+. Myosin phosphorylation is, therefore, the key event in actin activation of ATPase activity and initiation of contraction in skinned chicken gizzard fibers.
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M3 - Article
C2 - 6848377
AN - SCOPUS:0020646886
VL - 42
SP - 45
EP - 50
JO - Federation Proceedings
JF - Federation Proceedings
SN - 0014-9446
IS - 1
ER -