A G-protein of sarcoplasmic reticulum of skeletal muscle is activated by caffeine or inositol trisphosphate

Tohru Hasegawa, Shuzo Kumagai

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Here we show the activation of G-protein by inositol trisphosphate (IP3) or caffeine in sarcoplasmic reticulum (SR) of skeletal muscle and the consequent existence of a common mechanism of Ca2+ release from SR induced by caffeine and by IP3. (i) Indomethacin inhibits Ca2+ release induced by IP3 or caffeine. (ii) PGE1 does not induce Ca2+ release itself, but does stimulate Ca2+ release induced by IP3, or caffeine, from SR. (iii) Forskolin stimulates both types of Ca2+ release. The inhibitory effect of indomethacin on both forms of Ca2+ release, and the stimulatory effect of PGE1 and forskolin on either Ca2+ release suggest that there exists a common mechanism between IP3- and caffeine-induced Ca2+ release. (iv) Caffeine or IP3 activates G-protein via inhibition of a GTPase activity. (v) Indomethacin itself inactivates this G-protein by stimulation of a GTPase activity and reverses the activation of G-protein induced by IP3 or caffeine. (vi) PGE1 competes with the inhibitory effect of indomethacin on GTPase activity and PGE1 itself activates G-protein through inhibition of GTPase activity. From these results, it could be suggested that caffeine or IP3 induces Ca2+ release from the SR via activation of G-protein, which affects the Ca2+ channel and cAMP which seems to affect G-protein via A-kinase.

Original languageEnglish
Pages (from-to)283-286
Number of pages4
JournalFEBS Letters
Volume244
Issue number2
DOIs
Publication statusPublished - Feb 27 1989

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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