Effects of cAMP- and cGMP-dependent protein kinases, and calmodulin on Ca2+ uptake by highly purified sarcolemmal vesicles of vascular smooth muscle

Eiichi Suematsu, Masato Hirata, Hirosi Kuriyama

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Abstract

Sarcolemmal fractions of vascular smooth muscles were prepared from porcine thoracic aortae by differential and sucrose density gradient centrifugation. In these fractions, there was a high activity of 5′-nucleotidase, a putative marker enzyme of plasma membrane, and a low activity of rotenone insensitive NADH-cytochrome c reductase a marker of sarcoplasmic reticulum. In these fractions, the Ca2+ uptake was ATP-dependent. A low concentration of saponin which inhibited Ca2+ uptake by the plasma membrane but not by the sarcoplasmic reticulum, inhibited 65% of the Ca2+ uptake of this fraction. The Ca2+ uptake of this fraction was enhanced by cAMP- and cGMP-dependent protein kinases, and by calmodulin. The cAMP-dependent protein kinase enhanced the phosphorylation of 28 and 22 kDA proteins, while the cGMP-dependent protein kinase phosphorylated the 35 kDa protein. The phosphorylation of 100, 75, 65, 41 and 22 kDa proteins was enhanced by Ca2+ and calmodulin. These results indicate that cAMP- and cGMP-dependent protein kinases as well as calmodulin play important roles in Ca2+ transport in the sarcolemma, and that the phosphorylated proteins may be associated with an enhancement of Ca2+ transport in the sarcolemma.

Original languageEnglish
Pages (from-to)83-90
Number of pages8
JournalBBA - Biomembranes
Volume773
Issue number1
DOIs
Publication statusPublished - Jun 13 1984

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All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Cell Biology

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