Effect of protein kinase A on inositide metabolism and rap 1 G-protein in human erythroleukemia cells.

Abstract

Human erythroleukemia (HEL) cells phosphorylate [3H]inositol 1,4,5-trisphosphate to inositol 1,3,4,5-tetrakisphosphate; they also contain all the enzymes to sequentially dephosphorylate [3H]inositol 1,4,5-trisphosphate and [3H]inositol 1,3,4,5-tetrakisphosphate to inositol. alpha-Thrombin, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine, and sodium fluoride caused the formation of [3H]inositol phosphates in HEL cells that were previously labeled with [3H]inositol. This indicates agonist-induced activation of phospholipase C and hydrolysis of the inositol phospholipids. Pretreatment of the HEL cells with iloprost, a prostacyclin analog that increases cellular cyclic AMP levels, dramatically reduced the formation of inositol phosphates and the increase of [3H]phosphatidylinositol 4,5-bisphosphate. The inhibitory effects of iloprost were associated with the phosphorylation of a 24-kDa protein, which was detected with an antiserum obtained against the rap 1 protein. The catalytic subunit of protein kinase A inhibited formation of polyphosphoinositides during phosphorylation of the rap 1 protein in membranes. This rap 1 protein might have functional relevance in the inhibition of agonist-induced inositide metabolism.

• Authors: E R Lazarowski, D A Winegar, R D Nolan, E Oberdisse, E G Lapetina
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 265 Issue 22 Pg. 13118-23 (Aug 05 1990) ISSN: 0021-9258 [Print] United States
• PMID: 1695902 (Publication Type: Journal Article)

Chemical References

• Inositol Phosphates
• Membrane Proteins
• inositol-1,3,4,5-tetrakisphosphate
• Inositol
• Inositol 1,4,5-Trisphosphate
• Epoprostenol
• Protein Kinases
• Thrombin
• Iloprost

Topics

• Cell Line
• Cell Membrane (metabolism)
• Cytosol (metabolism)
• Epoprostenol (pharmacology)
• Humans
• Iloprost
• Inositol (metabolism)
• Inositol 1,4,5-Trisphosphate (metabolism)
• Inositol Phosphates (metabolism)
• Kinetics
• Leukemia, Erythroblastic, Acute
• Membrane Proteins (isolation & purification, metabolism)
• Phosphorylation
• Protein Kinases (metabolism, pharmacology)
• Thrombin (pharmacology)
• Tumor Cells, Cultured (drug effects, metabolism)