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Biomedical subjects

T Inazu

Publications and source records attributed to T Inazu.

45 records · Page 3Linked to original sources
PubMed1992

Protein-tyrosine phosphorylations induced by concanavalin A and N-formyl-methionyl-leucyl-phenylalanine in human neutrophils.

The ability of the lectin concanavalin A (ConA) and N-formyl-methionyl-leucyl-phenylalanine (fMLF) to induce protein-tyrosine phosphorylation in human neutrophils was examined by immunoblot analysis. ConA caused an increase in tyrosine phosphorylation of protein bands with apparent molecular masses of 120, 80, 76, 66 and 40 kDa; on the other hand, fMLF caused an increase in those of only 80-kDa and 40-kDa proteins. These protein-tyrosine phosphorylations were time- and dose-dependent. The tyrosine phosphorylation of 40-kDa protein induced by fMLF was suppressed but that by ConA was not suppressed by pertussis toxin pretreatment. At the same time, pertussis toxin pretreatment also inhibited lysozyme release and aggregation of neutrophils induced by fMLF but did not inhibit those responses induced by ConA. These results suggest that the tyrosine phosphorylation of 40-kDa protein may be involved in a part of neutrophil activation and be regulated via pleiotropic signal transduction pathways. In addition, immunoblot analysis employing antibodies against microtubule-associated protein 2 (MAP2) kinase suggested that this tyrosine-phosphorylated 40-kDa protein might be the MAP2 kinase.

Blood Proteins↗
PubMed1991

The lectin wheat germ agglutinin induces rapid protein-tyrosine phosphorylation in human platelets.

In response to wheat germ agglutinin (WGA), platelet aggregation and stimulation of protein-tyrosine phosphorylation were observed in a dose dependent manner. These reactions were completely inhibited by coexistence of N-acetyl-D-glucosamine with WGA. Upon stimulation by this agonist, protein-tyrosine phosphorylation of seven bands with molecular masses of 140-, 130-, 80-, 76-, 53-, 38- and 35-kDa proteins was observed by immunoblot. These protein-tyrosine phosphorylations were divided into three groups by kinetics. Considering the previous report from our laboratory that thrombin and collagen induced tyrosine phosphorylation in 135-, 124- and 76-kDa proteins (Nakamura, S. and Yamamura, H. (1989) J. Biol. Chem. 264, 7089-7091.), there may be another signal transduction pathway in tyrosine phosphorylation of human platelets.

Blood Platelets↗
PubMed1991

Possible endogenous substrate proteins for cytosolic protein-tyrosine kinase from porcine spleen.

1. Endogenous phosphate acceptor proteins by cytosolic protein-tyrosine kinase from porcine spleen (CPTK-40) were studied using subcellular fractions of porcine spleen and supernatant fraction of rat various tissues. 2. At least 13 phosphate acceptor proteins ranging from 94 to 26 kDa were observed in all but mitochondrial subcellular fractions. 3. Among the supernatant fraction of rat tissues, brain, testis and spleen contained many phosphate acceptor proteins. 4. The most heavily phosphorylated band of around 55 kDa which was commonly recognized among various tissues was confirmed as tubulin by the immunoreactivity with anti-tubulin antibody. 5. The results obtained in this paper indicate that CPTK-40 has the potential to catalyze the phosphorylation of numerous endogenous proteins including tubulin.

Animals↗
PubMed1990

Protein-tyrosine phosphorylation and aggregation of intact human platelets by vanadate with H2O2.

The ability of vanadate with H2O2 to stimulate protein-tyrosine phosphorylation and aggregation in intact human platelets was observed. Upon stimulation by these agents, there was a change in the amount of protein-tyrosine phosphorylation of four bands with molecular masses of 80-, 76-, 53- and 38-kDa proteins. The tyrosine phosphorylation in these four bands increased gradually and reached a maximum level at 2 min and then decreased. Aggregation of platelets was also induced by these agents in a dose dependent manner. The observation that the aggregation was preceded by the increase in tyrosine phosphorylation of these proteins suggests that tyrosine phosphorylation may be involved in an early stage of platelet aggregation.

Blood Platelets↗
PubMed1989

Phospholipids differently modulate the activity of cytosolic protein-tyrosine kinase from porcine spleen.

Effect of membrane phospholipids on the activity of cytosolic protein-tyrosine kinase from porcine spleen (CPTK-40) has been studied. Using poly(Glu Na, Tyr)4:1 as a substrate, phosphatidylethanolamine, phosphatidylcholine and phosphatidylserine had stimulatory effects on that phosphorylation activity, however phosphatidic acid had inhibitory and phosphatidylinositol had no effects. Similar results were obtained using[Val5]angiotensin II as a substrate. On the other hand using basic protein (H2B histone and myelin basic protein) as substrates, phosphatidic acid stimulated the activity of CPTK-40, while phosphatidylinositol inhibited the activity. Phosphatidylethanolamine, phosphatidylcholine and phosphatidylserine caused different effect on the activity of CPTK-40 depending on the substrate employed. However using acidic protein (tubulin and casein) as substrates, the activity of CPTK-40 was neither stimulated nor inhibited by any phospholipids. These results suggest that phospholipids may modulate the activity of CPTK-40.

Animals↗
PubMed1989

Effect of poly-basic amino acids on the phosphorylation of various substrate proteins by cytosolic protein-tyrosine kinase from porcine spleen.

Cytosolic protein-tyrosine kinase from porcine spleen (CPTK-40) is strongly activated by poly-L-lysine using bovine serum albumin, ovalbumin, phosphorylase b, calmodulin and H1 histone as substrate proteins. However, this polyamine inhibited the enzyme activities when myelin basic protein, tubulin and H2B histone were used as substrate proteins. These stimulatory and inhibitory effects on CPTK-40 are not specific for polylysine, but polyarginine and polyornithine have similar effects on this phosphorylation reaction. Effect of poly-basic amino acids on CPTK-40 seems to be mainly on the substrate proteins, rather than on the enzyme itself.

Animals↗
PubMed1989

Normoreninemic hypoaldosteronism in a case of isolated ACTH deficiency.

This paper documents the rare and hitherto unreported association between isolated ACTH deficiency and normoreninemic hypoaldosteronism in a 63-year-old woman. Baseline plasma aldosterone and 18-hydroxycorticosterone were extremely low. Both steroids did not respond to exogenous angiotensin II infusion, whereas they were increased in parallel to ACTH stimulation. Thus, acquired dysfunction or congenital dysgenesis of the zona glomerulosa was suspected. The upright posture-furosemide test showed a subnormal but definite plasma aldosterone response coupled with a normal increase in plasma renin activity, indicating that there may be a yet unidentified mechanism(s) underlying the postural increase of aldosterone.

17-Hydroxycorticosteroids↗