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Biomedical subjects

M Shimizu

Publications and source records attributed to M Shimizu.

At least 325 records · Page 18Linked to original sources
PubMed1999

The angiotensin II AT1 receptor antagonist candesartan at antihypertensive plasma concentrations reduces damage induced by ischemia-reperfusion.

The aim of this study was to investigate if the angiotensin II AT1 receptor antagonist candesartan in antihypertensive plasma concentrations improves myocardial function and limits infarct size in anesthetized pigs. Animals were subjected to 45 min of regional ischemia and 240 min of reperfusion. Starting 60 min before ischemia, two groups of pigs (n = 6 in each) received either candesartan (25 micrograms/kg bolus followed by a continuous infusion at a rate of 14 micrograms/kg/h) or the corresponding volume of vehicle throughout the study period. Left ventricular systolic segment shortening (%SS) was measured by sonomicrometry, and infarct size was determined by triphenyl tetrazolium chloride staining. The plasma concentration of candesartan during the experiment was between 100 and 150 nmol/L, which was considered to be within the therapeutic range. Neither candesartan nor vehicle affected hemodynamics or coronary blood flow prior to ischemia. Compared to vehicle, candesartan improved recovery of %SS in the ischemic area. At 240 min of reperfusion, the %SS was significantly higher in pigs given candesartan than in pigs given vehicle (7.1 +/- 0.87% vs-1 +/- 1.79%; p < 0.01). In both groups the area at risk was approximately 20% of the left ventricle. Infarct size as a percentage of the area at risk was significantly smaller in the candesartan group than in the vehicle group (46 +/- 3.0 vs 73 +/- 3.6%; p < 0.01). The results suggest that angiotensin II AT1 receptor blockade, obtained in antihypertensive plasma concentrations, supports myocardial functional recovery and limits infarct size.

Anesthesia↗
PubMed1999

Long-term follow-up of the changes in circulating cytokines, soluble cytokine receptors, and white blood cell subset counts in patients with rheumatoid arthritis (RA) after monoclonal anti-TNF alpha antibody therapy.

To investigate the mechanism of the long-lasting efficacy of chimeric monoclonal anti-TNFalpha antibody (cA2) therapy for rheumatoid arthritis (RA), eight patients with refractory RA were treated with a single infusion of cA2 and the changes in circulating cytokines (IL-1, IL-6, TNFalpha, and IL-10), soluble cytokine receptors (TNF-RI, RII, and sIL-6R) and peripheral white blood cell (WBC) subset counts were followed up long-term (12 weeks) after cA2 therapy in them. Significant clinical responses (>20% improvement according to Paulus' criteria) were observed just after cA2 infusion and lasted more than 4 weeks in all patients, as reported elsewhere. Moreover, five of the eight patients showed prolonged clinical responses (>12 weeks). The elevated serum IL-6 and sTNF-RI (or RII) levels before treatment rapidly decreased after treatment. The serum IL-10 levels also significantly elevated before treatment. The elevations of serum IL-10 levels were augmented after treatment and stayed higher than the baseline in four patients with prolonged clinical responses. No significant TNFalpha, IL-1alpha and -beta, or sIL-6R were detected in the sera of the patients before treatment and during the whole study period. On the other hand, peripheral lymphocytes as well as total WBC and neutrophils increased for 4 weeks after treatment. However, thereafter, only the lymphocyte count decreased gradually and stayed below the baseline long-term (12 weeks). FACS analysis revealed the predominance of T lymphocytes in the decrease in lymphocyte counts. These results suggest that the augmentation of IL-10 production and the decrease in T cells might partly contribute to the long-lasting efficacy of cA2 treatment in RA.

Adult↗
PubMed1999

Another cell death induction system: TNF-alpha acts as a ligand for Fas in vaginal cells.

The death receptor Fas transduces apoptotic death signaling upon stimulation with the Fas ligand. We previously reported that Fas contributes to vaginal cell death observed during the estrus cycle and after estrogen deprivation, using the functional Fas-lacking lpr and lprcg mutant mouse. In the present study, we investigated whether the Fas ligand also plays a dominant role in vaginal cell death using the functional Fas ligand-lacking gld mutant mouse. Our results demonstrated that vaginal cells of gld mice do not show any abnormalities, suggesting the possible presence of another ligand for Fas. Through our investigation, we demonstrated TNF-alpha as a ligand for vaginal Fas. Here, we propose that TNF-alpha acts for the ligand for Fas in vaginal cells, suggesting a new cell death induction system.

Animals↗
PubMed1999

Magnetic resonance imaging of experimentally-induced sialadenitis in rat submandibular glands.

OBJECTIVES: To correlate the features of magnetic resonance (MR) images of experimentally induced obstructive sialadenitis in rat submandibular glands with the histopathological changes. METHODS: Changes in MR images of ligated and non-ligated rat submandibular glands were compared with the histopathological changes and wet weight ratios. Spin echo T1 weighted images (SE T1WI), fast spin echo T2 weighted images (FSE T2WI), and gradient echo T2 weighted images (GE T2WI) were obtained at 1, 2, 3, 4, 5, 7 and 21 days after duct ligation with a 0.3 T MR imaging system. RESULTS: There was a significant difference (P<0.05) between the signal intensity ratios of both ligated and non-ligated glands on each day, except at 21 days on GE T2WI. On SE T1WI, small interval changes of signal intensity ratios were observed on both glands, whereas there were large interval changes at 1 - 2 days, 4 - 7 days and 21 days after duct ligation with FSE T2WI. These three periods correlated highly with three phases of histopathological changes, swelling of acinar cells at 1 - 2 days, atrophy of acinar cells and increase of duct-like structures at 3 - 7 days, and proliferation of connective tissue at 21 days, and the changes in wet weight ratios. A similar tendency was observed on GE T2WI to FSE T2WI. CONCLUSIONS: As FSE T2WI showed large changes in signal intensity that correlated highly with histopathological three phases, it is recommended as the MR sequence of choice for diagnosing the degree of damage in obstructive sialadenitis.

Animals↗
PubMed1999

Enhancer and silencer binding proteins involved in the rat cdc2 promoter activation at the G1/S boundary.

BACKGROUND: Expression of the rat cdc2 gene during G1-S phase progression is negatively and positively regulated by the silencer and enhancer elements located upstream of the basal promoter. The silencer and enhancer sequences resemble each other, but the silencer contains extra internal AG residues. RESULTS: The cDNA clones encoding the enhancer binding proteins cdc2E1 and cdc2E2 were isolated by South-Western blotting. cdc2E1 and cdc2E2 comprise 436 and 256 amino acids and have two RNA binding domains which contain an RNP1 octamer and an RNP 2 hexamer. Both cdc2E1 and cdc2E2 bind to the double-stranded and single-stranded silencer and enhancer sequences, but their binding affinity to the enhancer was stronger than that to the silencer. Transfection of quiescent 3Y1 cells with the cdc2 promoter-luciferase constructs, followed by serum stimulation, showed that the promoter activation at the G1-S phase boundary was reduced greatly by base substitutions within the enhancer, but not within the silencer. Gel shift assays with oligonucleotides containing both the silencer and enhancer showed that formation of the large complex was greatly reduced if base-substitutions were introduced into the enhancer, but not within the silencer. The complex was supershifted completely by anti-cdc2E1 antibody and partially by anti-cdc2E2 antibody. CONCLUSION: These results suggest that cdc2E1 and cdc2E2 preferentially form the multimeric complex at the enhancer site after the late G1 phase for activation of the cdc2 promoter.

Amino Acid Sequence↗
PubMed1999

Non-invasive quantitative detection and applications of non-toxic, S65T-type green fluorescent protein in living plants.

Green fluorescent protein (GFP) has emerged as a powerful new tool in a variety of organisms. An engineered sGFP(S65T) sequence containing optimized codons of highly expressed eukaryotic proteins has provided up to 100-fold brighter fluorescence signals than the original jellyfish GFP sequence in plant and mammalian cells. It would be useful to establish a non-invasive, quantitative detection system which is optimized for S65T-type GFP, one of the brightest chromophore mutants among the various GFPs. We demonstrate here that highly fluorescent transgenic Arabidopsis can be generated, and the fluorescence intensity of whole plants can be measured under non-disruptive, sterile conditions using a quantitative fluorescent imaging system with blue laser excitation. Homozygous plants can be distinguished from heterozygous plants and fully fertile progenies can be obtained from the analyzed plants. In the case of cultured tobacco cells, GFP-positive cells can be quantitatively distinguished from non-transformed cells under non-selective conditions. This system will be useful in applications such as mutant screening, analysis of whole-body phenomena, including gene silencing and quantitative assessments of colonies from microorganisms to cultured eukaryotic cells. To facilitate the elucidation of protein targeting and organelle biogenesis in planta, we also generated transgenic Arabidopsis that stably express the plastid- or mitochondria-targeted sGFP(S65T). Etioplasts in dark-grown cotyledons and mitochondria in dry seed embryos could be visualized for the first time in transgenic Arabidopsis plants under normal growing conditions.

Arabidopsis↗
PubMed1999

Purification and cDNA cloning of a protein derived from Flammulina velutipes that increases the permeability of the intestinal Caco-2 cell monolayer.

A new protein that decreases transepithelial electrical resistance (TEER) in the human intestinal Caco-2 cell monolayer was found in a water-soluble fraction of the mushroom Flammulina velutipes. This protein, termed TEER-decreasing protein (TDP), is not cytotoxic and does not induce cell detachment, but rapidly increases the tight junctional permeability for water-soluble marker substances such as Lucifer Yellow CH (Mr 457) through the paracellular pathway. TDP was isolated and purified from the aqueous extract of F. velutipes by chromatographic means. Purified TDP was found to be a simple, nonglycosylated protein without intermolecular disulfide bonds, and the apparent molecular mass as estimated by SDS/PAGE and gel filtration is 30 kDa. It was revealed that the N-terminal amino-acid sequence of purified TDP is identical to the recently reported N-terminal sequence of flammutoxin, a membrane-perturbing hemolytic protein, for which the complete primary structure has not yet been reported [Tomita, T., Ishikawa, D., Noguchi, T., Katayama, E., and Hashimoto, Y. (1998) Biochem. J. 333, 24794-24799]. The cDNA coding for TDP was cloned by 5' and 3' rapid amplification of cDNA ends. The ORF encodes a protein with 272 amino-acid residues showing no homology to known proteins. Relevant studies using TDP cDNA will provide insight into the structure-function relationships of membrane pore-forming toxins.

Amino Acid Sequence↗
PubMed1999

Solid-pseudopapillary carcinoma of the pancreas.

A case of solid-pseudopapillary carcinoma (SPC) of the pancreas in a 34-year-old Japanese woman is presented. An abdominal ultrasonography revealed a mass, which measured 10 cm in diameter, in the body and tail of the pancreas. The tumor was resected and it was originally diagnosed as a non-functioning islet cell tumor. One year and five months later, the patient was re-admitted to hospital, and liver metastasis was confirmed by ultrasonography. The patient died 6 days after the second transcatheter arterial embolization (TAE) required for the metastasis. The autopsy showed small foci of liver metastasis. A retrospective examination of the tumor suggested the diagnosis of SPC because of its characteristic solid and pseudopapillary structures, immunohistochemical findings, and liver metastasis. This case suggests that capsular invasion, specifically found at the surgical margin of the peritoneal side, may be an important pathological finding that is suggestive of malignant potential in solid-pseudopapillary tumor. If there is such a finding in a surgical specimen, an intensive follow up should be advised to the clinician.

Adult↗
PubMed1999

MIP-1alpha and MCP-1 contribute to crescents and interstitial lesions in human crescentic glomerulonephritis.

BACKGROUND: The precise molecular mechanisms of macrophage (Mphi) recruitment and activation in crescentic glomerulonephritis remain to be investigated. We hypothesized that locally produced macrophage inflammatory protein (MIP)-1alpha and monocyte chemoattractant protein (MCP)-1 via the chemokine receptors participate in the pathophysiology of human crescentic glomerulonephritis by recruiting and activating Mphi. METHODS: We investigated the levels of MIP-1alpha and MCP-1 by enzyme-linked immunosorbent assay (ELISA) in 20 healthy subjects, 20 patients with crescentic glomerulonephritis, and 41 control patients with various other renal diseases. The presence of MIP-1alpha, MCP-1, and the cognate chemokine receptor for MIP-1alpha, CCR5, in the diseased kidneys was evaluated by immunohistochemical and in situ hybridization analyses. RESULTS: MIP-1alpha-positive cells were mainly detected in crescentic lesions, whereas MCP-1 was mainly in the interstitium. In addition, we detected CCR5-positive cells in diseased glomeruli and interstitium. Urinary MIP-1alpha was detected in crescentic glomerulonephritis, even though it was below detectable levels in healthy subjects and in patients with other renal diseases without crescents. Urinary MIP-1alpha levels in the patients with crescentic glomerulonephritis were well correlated with the percentage of cellular crescents and the number of CD68-positive infiltrating cells and CCR5-positive cells in the glomeruli. However, urinary MCP-1 levels were well correlated with the percentage of both total crescents and fibrocellular/fibrous crescents and the number of CD68-positive infiltrating cells in the interstitium. Moreover, elevated urinary levels of both MIP-1alpha and MCP-1 dramatically decreased during glucocorticoid therapy-induced convalescence. CONCLUSIONS: These observations suggest that locally produced MIP-1alpha may be involved in the development of cellular crescents in the acute phase via CCR5 and that MCP-1 may be involved mainly in the development of interstitial lesions in the chronic phase when fibrocellular/fibrous crescents are present, possibly through Mphi recruitment and activation.

Adolescent↗
PubMed1999

Dietary prevention of azoxymethane-induced colon carcinogenesis with rice-germ in F344 rats.

The modifying effect of dietary administration of defatted rice-germ and gamma-aminobutyric acid (GABA)-enriched defatted rice-germ on azoxymethane (AOM)-induced colon carcinogenesis was investigated in two experiments with male F344 rats. In the first experiment (the pilot study), the effects of the defatted rice-germ, the GABA-enriched defatted rice-germ and rice-germ on AOM-induced (15 mg/kg body wt once a week for 3 weeks) formation of aberrant crypt foci (ACF) were examined. The latter two preparations (2.5% in the diet) significantly inhibited ACF formation (P < 0.005). In the second experiment, a long-term study of the effects of rice-germ was done. One group was treated with AOM alone, four groups received the carcinogen and were fed the diets containing 2.5% rice-germ or 2.5% GABA-enriched defatted rice-germ for 5 (initiation phase) or 30 weeks (post-initiation phase), two groups were treated with rice-germ or GABA-enriched defatted rice-germ alone and one group was kept on the basal diet. At the termination of the study, dietary exposure to rice-germ during the initiation phase significantly reduced the incidence of colonic adenocarcinoma (71 versus 29%, P < 0.01). GABA-enriched defatted rice-germ or rice-germ during the post-initiation phase also decreased the frequency of colonic adenocarcinoma (71 versus 20%, GABA-enriched defatted rice-germ feeding, P < 0.01; 27%, rice-germ feeding, P < 0.01). These data suggest that constituents of rice-germ are possible dietary preventatives for human colon cancers.

Animals↗
PubMed1999

Aminoguanidine supplementation delays the onset of senescence in vitro in dermal fibroblast-like cells from senescence-accelerated mice.

The effects of aminoguanidine supplementation on senescence acceleration in vitro were examined in fibroblasts from the dorsal dermis of newborn SAMP11 (accelerated senescence-prone mice), and were compared to the effects in cell lines from SAMR1 (accelerated senescence-resistant) mice. Four millimolar aminoguanidine supplementation significantly delayed the senescence/crisis in cell lines from SAMP11 mice, but did not affect the senescence/crisis in cell lines from SAMR1 mice. Flow cytometric analysis of the DNA content of confluent cells revealed that aminoguanidine supplementation significantly decelerated the increase in the number of tetraploid cells until senescence/crisis. Although mean concentrations of lipid peroxides in the primary cultures did not differ significantly, considerably higher lipid peroxidation was observed in some SAMP11 cultures, and aminoguanidine supplementation reduced them to the levels in SAMRI cultures. These results strongly suggest that oxidative stress derived from polyamine catabolism may contribute to the senescence acceleration in vitro in cell lines from SAMP11 mice.

Animals↗
PubMed1999

Anti-elongation factor-1alpha autoantibody in adult atopic dermatitis patients.

Adult atopic dermatitis (AD) patients develop severe facial lesions, which sometimes distribute in sun-exposed areas similar to the rash of systemic lupus erythematosus. To declare autoimmunity in the pathogenesis of AD, we investigated serum antinuclear antibody (ANA) in 256 adult AD patients and identified its ligands. A high titer of ANA was found in 31.3% of AD patients and 75% of the ANA showed a homogenous pattern. Sixty-five percent of ANA(+) sera reacted to a 52 kDa protein (p52) in HeLa cell immunoblots. By screening the HeLa cell cDNA expression library with anti-p52 sera, a clearly positive clone was isolated. The sequence of this cDNA was identical to human elongation factor (hEF)-1alpha. The eluate of IgG bound to hEF-1alpha-glutathione S-transferase (GST) fusion protein recognized a band at 52 kDa in a HeLa cell immunoblot, and stained Hep-2 cell nuclei and cytoplasma as reported in hEF-1alpha distribution. The anti-p52 AD sera recognized the hEF-1alpha-GST fusion protein. The anti-hEF-1alpha antibody-positive AD patients were characterized by higher facial involvement and lower white blood cell counts compared with antibody-negative patients. The present results suggest the possible involvement of autoimmunity in the pathogenesis of adult AD.

Adult↗
PubMed1999

A role of the C-terminal region adjacent to the zinc-fingers in the DNA binding ability of Rme1p, a regulator of meiosis in S. cerevisiae.

Rme1p is a zinc-finger protein and has a pivotal role in control of meiosis in Saccharomyces cerevisiae. The DNA binding domain of Rme1p consists of three zinc-finger segments and the C-terminal 16 amino acid residues (called C-TR). To examine the role of C-TR, a series of mutant Rme1p fused with maltose binding protein (MBP) were constructed, purified, and characterized, in terms of the DNA binding ability. The basic amino acid residues R287 and K290, and the hydrophobic residues F288, L292, 1295, and L296 play an important role for DNA binding, suggesting that the C-TR forms an amphipathic alpha-helix. Also, it was shown that the mutations in the basic amino acid residues abolish the repression and inhibition of spore formation by Rme1p in vivo. Hence, the C-TR is important for in vivo function of Rme1p.

Amino Acid Sequence↗
PubMed1999

Eotaxin contributes to renal interstitial eosinophilia.

BACKGROUND: A potent eosinophil chemotactic cytokine, human eotaxin, is directly chemotactic for eosinophils. Therefore, the specific expression of eotaxin in tissue might play a crucial role in tissue eosinophilia. However, the precise molecular mechanism of the recruitment and activation of eosinophils in human renal diseases remains to be investigated. We evaluated the role of eotaxin in the pathogenesis of human diffuse interstitial nephritis with marked infiltration of eosinophils. METHODS: In this study, we examined 20 healthy volunteers. 56 patients with primary or secondary glomerular diseases and two hypereosinophilic syndrome patients without renal involvement. Urinary and serum eotaxin levels were determined by an enzyme-linked immunosorbent assay. We also detected the presence of eotaxin protein immunohistochemically. RESULTS: On the one hand, urinary levels of eotaxin were significantly higher before the initiation of glucocorticoid administration in the patient with interstitial nephritis with marked infiltration of eosinophils. On the other hand, urinary eotaxin levels were not detected in any patients with nephrotic syndrome, interstitial nephritis without eosinophils, hypereosinophilic syndrome without renal involvement or other renal diseases. Serum eotaxin levels were not detected in any of the patients. Therefore, the detection of eotaxin in the urine was specific for renal interstitial eosinophilia. Moreover, endothelial cells, infiltrating mononuclear cells and renal epithelial cells in the tubulointerstitial lesions were immunostained with specific anti-eotaxin antibodies. Furthermore, the elevated urinary levels of eotaxin decreased dramatically during glucocorticoid-induced convalescence. HYPOTHESIS: We hypothesize that in situ expression of eotaxin may provide a new mechanism to explain the renal interstitial eosinophil infiltration.

Adolescent↗
PubMed1999

Sulfating-activity and stability of cDNA-expressed allozymes of human phenol sulfotransferase, ST1A3*1 ((213)Arg) and ST1A3*2 ((213)His), both of which exist in Japanese as well as Caucasians.

We recently found single amino acid substitutions ((213)Arg/His and (223)Met/Val) in polymorphic human phenol-sulfating phenol sulfotransferase (SULT: cDNAs encoding ST1A3, P PST or HAST1/2) among Caucasians and African-Americans. In a Japanese population (n = 143), allele frequencies of (213)Arg and (213)His were 83.2 and 16. 8%, respectively, but the (223)Val allele was not found. (213)His homozygosity was reportedly associated with both very low (>7-fold) sulfating activities of p-nitrophenol (at 4 microM) and low thermostability in platelets. Sulfating-activity determinations using recombinant (213)Arg- and (213)His-forms (ST1A3*1 and ST1A3*2, respectively) did not, however, reveal appreciable deficiency in [(35)S]3'-phosphoadenosine 5'-phosphosulfate (PAPS)-dependent sulfation of p-nitrophenol (4 microM) by ST1A3*2 (7.5 vs. 10.2 nmol/min/nmol SULT for ST1A3). Kinetic parameters for p-nitrophenol for p-nitrophenol sulfation supported the slight decrease in sulfating activities at 4 microM (K(m), 0.82 vs. 1.75 microM; V(max), 13.2 vs. 13.1 nmol/min/nmol SULT, respectively, for ST1A3*1 and *2). p-Nitrophenyl sulfate-dependent 2-naphthol sulfation by ST1A3*2 was 69% of that by ST1A3*1 (p<0.05). However, ST1A3*2 was remarkably unstable at 45 and 37 degrees C as compared to ST1A3*1. The lower p-nitrophenol sulfating activity of ST1A3*2 may explain the lower platelet p-nitrophenol sulfation in ST1A3*2 homozygotes. Protein instability and ST1A3 gene regulation may be both involved in the polymorphism of p-nitrophenol sulfation in human tissues.

Arylsulfotransferase↗
PubMed1999

Interconversion of Mn(2+)-dependent and -independent protein phosphatase 2A from human erythrocytes: role of Zn(2+) and Fe(2+) in protein phosphatase 2A.

Human erythrocyte Mn(2+)-dependent (C'A') and -independent (CA) protein-serine/threonine phosphatase (PP) 2A are composed of 34-kDa catalytic C' and C subunits, in which the metal dependency resides, and 63-kDa regulatory A' and A subunits, respectively. Each catalytic and regulatory subunit gave the same V8- and papain-peptide maps, respectively. Stoichiometric zinc and substoichiometric iron were detected in CA but not in C'A' [Nishito et al. (1999) FEBS Lett. 447, 29-33]. The Mn(2+)-dependent protein-tyrosine phosphatase (PTP) activity of C'A' was about 70-fold higher than that of CA. Pre-incubation of CA with 25 mM NaF changed CA to a Mn(2+)-dependent form with higher PTP activity. The same NaF treatment had no effect on C'A'. Pre-incubation of C'A' with ZnCl(2), zinc-metallothionein, or FeCl(2) activated the Mn(2+)-independent PP activity, but pre-incubation with FeCl(3) did not. Ascorbate in the pre-incubation and assay mixture significantly stimulated the effect of FeCl(2). Pre-incubation of C'A' with 5 microM ZnCl(2) and 15 microM FeCl(2) in the presence of 1 mM ascorbate synergistically stimulated the Mn(2+)-independent PP activity, with concomitant suppression of the Mn(2+)-dependent PP and PTP activities. The PP and PTP activities of CA were unaffected by the same zinc and/or iron treatment. Micromolar concentrations of vanadate strongly inhibited the Mn(2+)-dependent PP activity of C'A' but only slightly inhibited the PP activity of CA. Using the distinct effect of vanadate as an indicator, the interconversion between CA and C'A' with the above mentioned treatments was proved. These results support the notion that Mn(2+)-independent CA is a Zn(2+)- and Fe(2+)-metalloenzyme, whose apoenzyme is Mn(2+)-dependent C'A'.

Animals↗
PubMed1999

Studies on functions of the 63-kDa A- and 74-kDa B'(delta)-regulatory subunits in human erythrocyte protein phosphatase 2A: dissociation and reassociation of the subunits.

A heterodimeric form, CA, of protein-serine/threonine phosphatase (PP) 2A purified from human erythrocytes was dissociated into a 34-kDa catalytic subunit C and 63-kDa inactive subunit A by Sephacryl S-200 gel filtration in the presence of 6 M urea. Reassociation of the C- and A-subunits in the absence of urea suppressed the PP activity of the C subunit toward phosphorylase a, P-H2B histone, and P-H1 histone in the presence or absence of 20 mM MnCl(2) or 50 mM Mg(CH(3)COO)(2), but stimulated the PP activity toward P-H1 histone in the presence of 200 mM NaCl and the Mn(2+)-dependent protein-tyrosine phosphatase (PTP) activity toward P-Tyr-Glu copolymers. The 74-kDa inactive B'(delta) subunit was isolated from a heterotrimeric form, CAB'(delta), of PP2A partially purified from human erythrocytes, by heparin-Sepharose column chromatography. The B'(delta) subunit reassociated with CA and suppressed the PP- and PTP-activities of CA. The B'(delta) subunit did not associate with the isolated C subunit directly, and had no effect on the activities of the C subunit, indicating that the A subunit is essential for the association of the B'(delta) subunit with CA and the resulting suppression of the PP- and PTP-activities.

Chromatography, Gel↗