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Ras proteins increase Ca 2+ ‐responsiveness of smooth muscle contraction
Author(s) -
Satoh S.,
Rensland H.,
Pfitzer G.
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)81395-g
Subject(s) - gtp' , phosphorylation , chemistry , contraction (grammar) , tyrosine , tyrosine kinase , g protein , microbiology and biotechnology , receptor , biochemistry , biophysics , biology , endocrinology , enzyme
G‐proteins may be involved in receptor‐mediated Ca 2+ ‐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 Ca 2+ (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 Ca 2+ ‐sensitizing effect of GTPγS and vasoconstrictors in mesenteric microarteries which may involve tyrosine phosphorylation.