Ras proteins increase Ca2+‐responsiveness of smooth muscle contraction
- 14 June 1993
- journal article
- Published by Wiley in FEBS Letters
- Vol. 324 (2) , 211-215
- https://doi.org/10.1016/0014-5793(93)81395-g
Abstract
G-proteins may be involved in receptor-mediated Ca2+-sensitization of smooth muscle contraction, but the responsible G-proteins are not yet known. Here we show that in β-escin skinned mesenteric microarteries, H-ras p21 proteins, preactivated with GTP or GTP γ S, increase force at constant submaximal Ca2+ (pCa 6.3) concentration dependently. The GTP-bound form of the wild-type H-ras p21 and the oncogenic mutant (p21[G12V]) were equally effective. The nucleotide-free and the inactive GDP-bound form of ras p21 had no effect on force. The tyrosine kinase inhibitor, tyrphostin, partially reversed the effect of the ras proteins in the GTP-bound form on force. Thus, ras proteins mimic the Ca2+-sensitizing effect of GTPγS and vasoconstrictors in mesenteric microarteries which may involve tyrosine phosphorylation.Keywords
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