scholarly journals Involvement of calcium-sensitive phospholipid-dependent protein kinase in control of acid secretion by isolated rat parietal cells

1985 ◽  
Vol 232 (2) ◽  
pp. 609-611 ◽  
Author(s):  
N G Anderson ◽  
P J Hanson
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Acid Secretion ◽  
Phorbol Esters ◽  
Inhibitory Effect ◽  
Dependent Protein Kinase ◽  
Kinase C ◽  
Protein Kinase C Activity ◽  
Dependent Protein ◽  
Isolated Rat

The relative potency with which phorbol esters inhibited histamine-stimulated aminopyrine accumulation (an index of acid secretion) paralleled that which has been established for the activation of purified protein kinase C. The inhibitory effect of 1-oleoyl-2-acetylglycerol on aminopyrine accumulation stimulated by various secretagogues was similar to that of 12-O-tetradecanoylphorbol 13-acetate. Protein kinase C activity was present in a parietal-cell-enriched fraction. In conclusion, protein kinase C could be involved in mechanisms regulating gastric acid secretion.

Autoregulation of muscarinic and gastrin receptors on gastric parietal cells

1989 ◽  
Vol 256 (2) ◽  
pp. G356-G363 ◽  
Author(s):  
T. Chiba ◽  
S. K. Fisher ◽  
B. W. Agranoff ◽  
T. Yamada
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Parietal Cell ◽  
Phorbol Esters ◽  
Cell Function ◽  
Inhibitory Effect ◽  
Parietal Cells ◽  
Kinase C ◽  
Protein Kinase C Activity ◽  
Inositol Phospholipids

In previous studies we demonstrated that parietal cell stimulation with gastrin and carbamoylcholine (carbachol) is accompanied by increased turnover of membrane inositol phospholipids. We conducted the present studies to examine whether membrane-associated protein kinase C activity is enhanced as a consequence of these events and to explore the role of this enzyme in regulating parietal cell function. We observed that carbachol and gastrin dose dependently increased membrane-associated protein kinase C activity while histamine did not. Furthermore, compounds such as phorbol esters and diacylglycerol, which are known to be direct stimulants of protein kinase C activity, also stimulated parietal cell aminopyrine uptake. In contrast, the phorbol ester 12-O-tetradecanoylphorbol-13-acetate and the synthetic diacylglycerol 1-oleoyl-2-acetyl-sn-glycerol inhibited both aminopyrine uptake and membrane inositol phospholipid turnover in parietal cells induced by carbachol and gastrin. The inhibitory effect appeared to result from reduction in the quantity of muscarinic and gastrin receptors without alterations in their specific affinities. These data suggest that protein kinase C mediates stimulation of parietal cells by gastrin and carbachol but also activates an autoregulatory mechanism via downregulation of muscarinic and gastrin receptors.

Calcium-dependent Protein Kinase Reactions Associated with Parotid Gland Secretory Granule Membranes

1987 ◽  
Vol 66 (2) ◽  
pp. 557-563 ◽  
Author(s):  
F. Dowd ◽  
E.L. Watson ◽  
Y.-S. Lau ◽  
J. Justin ◽  
J. Pasieniuk ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Secretory Granule ◽  
Dependent Protein Kinase ◽  
Calcium Dependent ◽  
Kinase C ◽  
Protein Kinase C Activity ◽  
Granule Membrane ◽  
Dependent Protein ◽  
Calcium Dependent Protein Kinase

Rat parotid secretory granule membranes were examined for the presence of calcium-dependent protein kinase activities and kinase substrates. Protein kinase C (C-kinase), which is stimulated by certain phospholipids, was present in the membranes, as indicated by its ability to catalyze the phosphorylation of histone. Two substrates for protein kinase C were seen in the granule membranes. The cytosolic fraction from the cell contained kinase activity, which was stimulated by phosphatidylserine and which caused the phosphorylation of two granule membrane polypeptides. In addition, when both granule membranes and cytosol were incubated together, phosphorylation of the cytosolic substrates was inhibited, indicating that the granule membrane substrates were phosphorylated preferentially. The results indicate that the granule membranes may react with cytosolic protein kinase C activity in a way which would direct an intracellular calcium and diacylglycerol signal toward the granule membrane. Since these signals occur during stimulation by various agonists, the mechanism may contribute to secretion.

scholarly journals Ca2+-independent binding of [3H]phorbol dibutyrate to protein kinase C is supported by protamine and other polycations

1988 ◽  
Vol 255 (2) ◽  
pp. 417-422 ◽  
Author(s):  
N T Thompson ◽  
R W Bonser ◽  
H F Hodson ◽  
L G Garland
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phorbol Esters ◽  
Deae Cellulose ◽  
Dependent Protein Kinase ◽  
Independent Manner ◽  
Protamine Sulphate ◽  
Phorbol Dibutyrate ◽  
Kinase C ◽  
Dependent Protein

The activity of the Ca2+- and phospholipid-dependent protein kinase, protein kinase C (PKC), can be modulated by diacylglycerols and phorbol esters. The association of these agents with PKC is, in turn, generally understood to be dependent on Ca2+ and phospholipids. Certain substrates, e.g. protamine sulphate, are known to undergo cofactor-independent phosphorylation by PKC. We report here that, in the presence of such substrates, PKC bound 1,2-dihexanoylglycerol and phorbol dibutyrate in a Ca2+-independent manner. Histone IIIs, which is phosphorylated by PKC only in the presence of Ca2+ and phospholipid, also supported Ca2+-independent binding of 1,2-dihexanoylglycerol and phorbol dibutyrate to PKC, but to a lesser extent than did protamine. Support for Ca2+-independent binding was also exhibited by non-peptide polycations (e.g. DEAE-cellulose DE52), indicating that recognition of the catalytic site is not a prerequisite for this effect. The natural polyamines spermine and putrescine did not have this property, however. The affinity of PKC for phorbol dibutyrate and 1,2-dihexanoylglycerol was found to be unchanged by the presence of substrates or DE52. It is proposed that, in the absence of Ca2+, certain polycations favour expression of the diacylglycerol/phorbol ester binding site by stabilizing the active conformation of PKC.

Calcium-activated, phospholipid-dependent protein kinase in pancreatic acinar cells

1985 ◽  
Vol 248 (6) ◽  
pp. G692-G701 ◽  
Author(s):  
M. Noguchi ◽  
H. Adachi ◽  
J. D. Gardner ◽  
R. T. Jensen
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phorbol Esters ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Protein Kinase Activity ◽  
Dependent Protein Kinase ◽  
Calcium Dependent ◽  
Kinase C ◽  
Dependent Protein

In the present study we partially purified calcium-activated, phospholipid-dependent protein kinase (protein kinase C) from pancreatic acinar cells of the guinea pig using diethylaminoethylcellulose and Sephadex G-150 chromatography and characterized the dependence of the enzyme on calcium, phospholipids, diacylglycerol (diolein), and the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA). The enriched preparation of protein kinase C contained no cyclic nucleotide-dependent or calcium-dependent, calmodulin-dependent protein kinase activity. The values of Km for H1-histone and ATP were 0.74 +/- 0.22 and 13.1 +/- 3.2 microM, respectively. Pancreatic protein kinase C demonstrated an absolute requirement for calcium and phospholipid for its activation, and diolein or TPA increased the affinity of the enzyme for calcium by 10-fold. With phosphatidylserine the calcium concentration that caused a half-maximal activation (Ka) was 74 +/- 17 microM, whereas with phosphatidylserine and diolein or TPA the Ka for calcium was 7.9 +/- 1.6 or 6.8 +/- 1.3 microM, respectively. Adding phosphatidylethanolamine and phosphatidylserine decreased the Ka for calcium to 2.0 +/- 0.9 microM with diolein and to 0.7 +/- 0.4 microM with TPA. Activation of protein kinase C by TPA and diolein was identical with calcium concentrations greater than 1 microM, but at low calcium concentrations (less than 1 microM) in the presence of phospholipids, maximally effective concentrations of diolein caused only 55% of the activation seen with TPA. In addition to TPA, other phorbol esters such as phorbol dibutyrate and phorbol diacetate, but not phorbol itself, activated protein kinase C.(ABSTRACT TRUNCATED AT 250 WORDS)

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