Korean J Physiol Pharmacol.
2000 Jun;4(3):211-217.
Tyrosine phosphorylation of paxillin may be involved in vascular smooth muscle contraction
- Affiliations
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- 1Department of Pharmacology, College of Medicine, Chungbuk National University, Chongju, Korea.
Abstract
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Paxillin is a regulatory component of the complex of cytoskeletal
proteins that link the actin cytoskeleton to the plasma membrane.
However, the role of paxillin during smooth muscle contraction is
unclear. We investigated a possible role for the membrane-associated
dense plaque protein paxillin in the regulation of contraction in rat
aortic vascular smooth muscle. The tyrosine phosphorylation of
paxillin, which was increased by norepinephrine, reached a peak level
after 1 min stimulation and then decreased with time. However,
norepinephrine induced a sustained contraction that reached a steady
state 30 min after application. Pretreatment with tyrphostin, an
inhibitor of tyrosine kinase, inhibited the tyrosine phosphorylation of
paxillin and also the contraction stimulated by norepinephrine. Both
inhibitions were concentration-dependent, and the degree of correlation
between them was high. These results show that, in rat aortic smooth
muscle, tyrosine kinase(s) activated by norepinephrine may
phosphorylate the tyrosine residues of paxillin, thereby providing a
source of regulation during vascular smooth muscle contraction.