Specific substrate for histone kinase II: a synthetic nonapeptide

Lipocortin I is not accessible for protein kinase C bound to the cytoplasmic surface of the plasma membrane in streptolysin-O-permeabilized pig granulocytes

We previously observed a 38 kDa protein that was a major protein component of the cytosolic extract of pig granulocytes and the dominant substrate of protein kinase C at supra-physiological Ca2+ concentrations. The purified 38 kDa protein itself required Ca2+ to be phosphorylated by protein kinase C. Now we demonstrate that this protein, which is also present in human granulocytes, is identical to lipocortin I. The identification is based on the chromatographic properties and immunoblot of the purified protein which is also a good substrate for tissue transglutaminase. Phosphorylation of lipocortin I by protein kinase C was investigated in granulocytes permeabilized with streptolysin-O. At physiological intracellular Ca2+ concentrations lipocortin I was not phosphorylated at all. At supra-physiological Ca2+ concentrations (0.5 mM), lipocortin I was also not phosphorylated when protein kinase C was translocated to the membrane by treatment of the cells with phorbol myristate acetate. Its phosphorylation was detectable only in control experiments when protein kinase C was activated in the cytosol by the addition of dioleoylglycerol and phosphatidylserine to the permeabilized cells. The data presented show that, in permeabilized granulocytes, Ca(2+)-lipocortin is not formed at physiological Ca2+ concentrations, and at supra-physiological Ca2+ concentrations the Ca(2+)-lipocortin I is not accessible to protein kinase C bound to the cytoplasmic surface of the plasma membrane.

Synthetic oligopeptide substrates which fail to compete with H1 histone for type II and type III isoenzymes of protein kinase C

1. The oligopeptide AAASFKAKK which contains recognition motifs similar to that found in the surrounding of the site of H1 histone phosphorylated by protein kinase C is unable to compete with H1 histone for the type II and type III isoenzymes, though it is a good substrate for protein kinase C and it is able to compete with a physiological substrate of the enzyme. 2. Among several oligopeptides tested as an alternative substrate a very basic peptide proved to be the most effective inhibitor of H1 histone phosphorylation. This oligopeptide substrate contains basic recognition motifs at both sides of the phosphorylated residue at variance with the sequence of H1 histone in the surrounding of the phosphorylated site.

Impaired translocation of protein kinase C activity in human non-insulin-dependent diabetes mellitus

Calcium- and phospholipid-dependent protein kinase (protein kinase C; PKC) may be an important mediator in transduction of some of the cellular actions of insulin. We studied PKC activity in freshly isolated circulating mononuclear cells obtained from healthy subjects and patients with non-insulin-dependent (type II) diabetes mellitus (NIDDM). The kinase activity was measured using a specific nonapeptide substrate, Ala-Ala-Ala-Ser-Phe-Lys-Ala-Lys-Lys-amide. There was negligible calcium- and phospholipid-independent kinase activity in cytosolic and particulate fractions of cells from both control and diabetic subjects. Total (cytosolic and particulate) PKC activity of mononuclear cells from poorly controlled diabetic patients was significantly reduced compared with controls; this reduction was mainly due to a decrease in the cytosolic kinase activity. Tumor-promoting phorbol ester (TPA, 0.1 mumol/L) induced translocation of PKC activity in control cells; in contrast, this subcellular redistribution was not observed in cells from a majority of poorly controlled diabetic subjects. Increased calcium influx into the cells caused by the calcium ionophore A23187-triggered translocation of PKC activity in control cells, while it was ineffective in cells from poorly controlled diabetic patients. Cells from well-controlled diabetic patients demonstrated TPA-induced translocation of the PKC activity approaching that of control cells. The total PKC activity in cells from patients with good glycemic control was normal. Impaired activation of PKC is thus associated with the insulin resistance found in patients with poorly controlled NIDDM.(ABSTRACT TRUNCATED AT 250 WORDS)

The 38 kDa Ca2+/membrane-binding protein of pig granulocytes needs a high Ca2+ concentration to be phosphorylated by protein kinase C

The 38 kDa Ca2+/membrane-binding protein reported to be the dominant substrate of protein kinase C in the extracts of pig neutrophil granulocytes was purified partially and its phosphorylation was investigated. In pig granulocytes type II protein kinase C was the major isoform, while type III isoenzyme was present only as a minor activity. Phosphorylation of the 38 kDa protein was performed with rat brain protein kinase C. Each of the three isoenzymes purified from rat brain was able to phosphorylate this protein, though on the conditions used in our experiments it was phosphorylated most intensively by type II protein kinase C. A phospholipid-dependent, but Ca2(+)-independent, form of protein kinase C was demonstrated with the aid of a synthetic oligopeptide substrate. Phosphorylation of the 38 kDa protein by the Ca2(+)-independent enzyme proceeded exclusively in the presence of Ca2+. The Ca2+ concentration necessary for the phosphorylation of the 38 kDa by either form of protein kinase C was by orders of magnitude higher than that required for the activation of protein kinase C.

Dual effect of arachidonic acid on protein kinase C isoenzymes isolated from rabbit thymus cells

Type II and type III isoenzymes of protein kinase C isolated from rabbit thymus cells were activated at relatively low concentrations but were inhibited at higher concentrations of arachidonic acid. Activation by cis-unsaturated fatty acids required Ca2+; the maximal activity was approached at about 10(-6) M Ca2+ concentration. The kinetics of activation and inhibition by arachidonic acid depended strongly on the nature of the substrate (synthetic oligopeptide or H1 histone), on the concentration of the protein substrate and on the stage of purification of the isoenzyme preparation investigated. Activation seemed to be favoured at high protein concentrations.

A synthetic peptide substrate for selective assay of protein kinase C

Among various phosphate acceptor proteins and peptides so far tested, a synthetic peptide having the sequence surrounding Ser(8) of myelin basic protein, Gln-Lys-Arg-Pro-Ser(8)-Gln-Arg-Ser-Lys-Tyr-Leu, (MBP4-14), is the most specific and convenient substrate which can be used for selective assay of protein kinase C. This peptide is not phosphorylated by cyclic AMP-dependent protein kinase, casein kinases I and II, Ca2+/calmodulin-dependent protein kinase II, or phosphorylase kinase, and can be routinely used for the assay of protein kinase C with low background in the crude tissue extracts. The Km value is considerably low (7 microM) with a Vmax value of twice as much as that for H1 histone.

Two components of type III protein kinase C with different substrate specificities and a phospholipid-dependent but Ca2+-inhibited protein kinase in rat brain

The activities of rat brain protein kinase C isoenzymic fractions separated by hydroxyapatite chromatography were measured with histone H1 or the oligopeptide Ala-Ala-Ala-Ser-Phe-Lys-Ala-Lys-Lys-amide as substrates. The oligopeptide was a better substrate than histone H1 for nearly all of the protein kinase C fractions. Two subfractions of type III isoenzyme were resolved (IIIa and IIIb); type IIIb was characterized by a very low histone kinase activity compared to its peptide kinase activity. In some brain extracts a phospholipid-dependent but Ca2+-inhibited protein kinase was also observed which was eluted from the hydroxyapatite column between type II and III isoenzymes of protein kinase C.

Protein kinase C in larval brain of wild-type and dunce memory-mutant Drosophila

Protein kinase C activity has been measured in extracts of larval brain of Drosophila melanogaster, with the synthetic nonapeptide substrate Ala-Ala-Ala-Ser-Phe-Lys-Ala-Lys-Lys-amide. Protein kinase C activity in such extracts is abolished in a Ca2+-dependent manner at 18 degrees C, and partly converted to a form independent of effectors. The decay of protein kinase C activity can be prevented by leupeptin or a crude calpastatin preparation isolated from fly heads, indicating the presence of the Ca2+-dependent neutral protease, calpain, in larval brains. The total protein kinase C levels were nearly the same in wild type and three different dunce "memory-mutant" strains. In contrast, the soluble/particulate activity ratios were different: wild-type, 0.91; dunce M11, 0.46; dunce M11/Df(1)dm75e19, 1.23; dunce2, 0.88. These data suggest that the membrane adherence of protein kinase C in larval brain is governed by the actor of genes other than dunce.

The phosphorylation site of Ca(2+)-dependent protein kinase from alfalfa

A 50 kDa, calcium-dependent protein kinase (CDPK) was purified about 1000-fold from cultured cells of alfalfa (Medicago varia) on the basis of its histone H1 phosphorylation activity. The major polypeptide from bovine histone H1 phosphorylated by either animal protein kinase C (PK-C) or by the alfalfa CDPK gave an identical phosphopeptide pattern. The phosphoamino acid determination showed phosphorylation of serine residues in histone H1 by the plant enzyme. Histone-related oligopeptides known to be substrates for animal histone kinases also served as substrates for the alfalfa kinase. Both of the studied peptides (GKKRKRSRKA; AAASFKAKK) inhibited phosphorylation of H1 histones by bovine and alfalfa kinases. The results of competition studies with the nonapeptide (AAASFKAKK), which is a PK-C specific substrate, suggest common features in target recognition between the plant Ca(2+)-dependent kinase and animal protein kinase C. We also propose that synthetic peptides like AAASFKAKK can be used as a tool to study substrates of plant kinases in crude cell extracts.

Isoenzyme patterns of protein kinase C and a phospholipid-dependent but Ca2+-inhibited enzyme fraction in the crude extracts of different tissues

We compared the protein kinase C isoenzyme patterns of crude extracts of rabbit brain, cerebellum, spleen, thymus and human and pig granulocytes. The isoenzymes were fractionated by hydroxyapatite chromatography and the protein kinase C activity was determined with a synthetic oligopeptide substrate. In the extracts of several tissues we also observed an enzyme fraction which was activated by phosphatidylserine + diacylglycerol but inhibited by Ca2+.

Subcellular distribution of protein kinase C in rat adrenal glomerulosa cells

With the aid of a synthetic nonapeptide which is a selective substrate for protein kinase C the activity of this enzyme was determined in the crude cytosolic and particulate fractions of rat adrenal glomerulosa cells. When the cells were sonicated in the presence of Ca2+ chelators 65 per cent of their total protein kinase C activity was found in the cytosolic extract. The treatment of cells with angiotensin II under conditions where the maximal stimulation of inositol-lipid hydrolysis was observed did not cause a statistically significant change in the apparent subcellular distribution of protein kinase C. However, when the cytosolic extract was prepared in the presence of Ca2+ the protein kinase C activity was recovered nearly exclusively from the particulate fraction.

Proteolytic activation of protein kinase C in the extracts of cells treated for a short time with phorbol ester

A 10 min treatment of human neutrophils with phorbol 12-myristate 13-acetate (PMA) has been reported to induce accumulation of the proteolytically activated Ca2+/phospholipid-independent catalytic fragment of protein kinase C in the cytosol of intact cells [(1986) J. Biol. Chem. 261, 4101-4105]. We investigated the proteolytic conversion of protein kinase C to Ca2+/phospholipid-independent form in the cytosol and membrane fractions of pig neutrophils. The activity of protein kinase C was measured with its specific oligopeptide substrate Ala-Ala-Ala-Ser-Phe-Lys-Ala-Lys-Lys-amide designed previously. In our experiments the short-term treatment of neutrophils with PMA did not induce the accumulation of the proteolytically activated form of protein kinase C in the cytosol of intact cells. However, treatment of cells with PMA enhanced the limited proteolysis of protein kinase C during the preparation of cell extracts.

Isolation, characterization, and expression of the gene encoding the late histone subtype H1-gamma of the sea urchin Strongylocentrotus purpuratus

We cloned and characterized the gene encoding H1-gamma, a late histone subtype of the sea urchin species Strongylocentrotus purpuratus. The predicted primary sequence of H1-gamma is 216 amino acids in length and has a net charge of +70, which is high for a somatic H1 histone. The H1-gamma gene appears to be a unique sequence gene that is not tightly linked to the core histone genes. The 770-base-pair transcribed region of the H1-gamma gene is bordered on the 5' side by two previously described H1-specific sequence elements and on the 3' side by a hairpin loop structure and CAGA box sequences. We detected 3,900 stored maternal H1-gamma mRNA transcripts per egg. The number of H1-gamma transcripts per embryo rises by 9.5 h postfertilization, but the maximum rate of accumulation (4,300 molecules per min per embryo) occurs in the late-blastula-stage embryo between 14 and 21 h after fertilization. The number of H1-gamma mRNA molecules peaks 21 h after fertilization when there are 2.0 X 10(6) molecules per embryo (a 500-fold increase) and then decreases over the next 3.25 h to 1.3 million molecules per embryo. Between 24 and 82 h after fertilization the number of H1-gamma transcripts declines steadily (210 molecules per min per embryo) to reach approximately 5.4 X 10(5) H1-gamma mRNAs by 82 h postfertilization. Surprisingly, the number of late H1 mRNA molecules per embryo is greater than the number of late H2B mRNA molecules beginning at the early gastrula stage of development.

Isolation, characterization, and expression of the gene encoding the late histone subtype H1-gamma of the sea urchin Strongylocentrotus purpuratus

We cloned and characterized the gene encoding H1-gamma, a late histone subtype of the sea urchin species Strongylocentrotus purpuratus. The predicted primary sequence of H1-gamma is 216 amino acids in length and has a net charge of +70, which is high for a somatic H1 histone. The H1-gamma gene appears to be a unique sequence gene that is not tightly linked to the core histone genes. The 770-base-pair transcribed region of the H1-gamma gene is bordered on the 5' side by two previously described H1-specific sequence elements and on the 3' side by a hairpin loop structure and CAGA box sequences. We detected 3,900 stored maternal H1-gamma mRNA transcripts per egg. The number of H1-gamma transcripts per embryo rises by 9.5 h postfertilization, but the maximum rate of accumulation (4,300 molecules per min per embryo) occurs in the late-blastula-stage embryo between 14 and 21 h after fertilization. The number of H1-gamma mRNA molecules peaks 21 h after fertilization when there are 2.0 X 10(6) molecules per embryo (a 500-fold increase) and then decreases over the next 3.25 h to 1.3 million molecules per embryo. Between 24 and 82 h after fertilization the number of H1-gamma transcripts declines steadily (210 molecules per min per embryo) to reach approximately 5.4 X 10(5) H1-gamma mRNAs by 82 h postfertilization. Surprisingly, the number of late H1 mRNA molecules per embryo is greater than the number of late H2B mRNA molecules beginning at the early gastrula stage of development.