Cyclic AMP-dependent protein kinase interferes with GTP gamma S stimulated IP3 formation in differentiated HL-60 cell membranes.
The effects of addition of activated cyclic AMP-dependent protein kinase (PKA) on the function of islet-activating protein (IAP)-sensitive GTP-binding (G) protein were studied in the plasma membranes of 3H-inositol-labeled differentiated human leukemic (HL-60) cells. Pretreatment of the membranes with activated PKA (0.1 mg/ml) in the presence of MgATP for 15 min. at 37 degrees C decreased GTP gamma S-stimulated inositol trisphosphate (IP3) formation by about 30%, but had no influence on Ca2+-stimulated IP3 formation. And autoradiography in the phosphorylation experiments of solubilized HL-60 cell membranes by PKA showed some 32P incorporated bands, and among them one of the major bands showed the migration at 40 kDa supporting that the G protein coupling with PI response was phosphorylated by PKA. These results showed that pretreatment with activated PKA inhibited the mediating function of the G protein between the fMLP receptor and phospholipase C by its phosphorylation.
Misaki
N
N
Department of Pharmacology I, Osaka University, School of Medicine, Japan.
Imaizumi
T
T
Watanabe
Y
Y
D002118:Calcium / Q000502:physiology; D002454:Cell Differentiation; D002462:Cell Membrane / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000378:metabolism; D013873:Thionucleotides; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism
D007295:Inositol Phosphates; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D011494:Protein Kinases; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D002118:Calcium