The mechanism of protein kinase regulation by protein phosphatases

2001 ◽  
Vol 29 (4) ◽  
pp. 385-391 ◽  
Author(s):  
D. Barford
Keyword(s):  
Protein Kinase ◽  
Insulin Receptor ◽  
Protein Kinases ◽  
Protein Phosphatases ◽  
Important Class ◽  
Cyclin Dependent Kinase ◽  
Receptor Kinase ◽  
Dual Specificity Phosphatase ◽  
Dual Specificity ◽  
Insulin Receptor Kinase

Protein kinases are an important class of substrate of the protein phosphatases. We have examined the mechanism of dephosphorylation of the activation segments of the insulin receptor kinase and cyclin-dependent kinase 2 by their respective phosphatases, namely the tyrosine specific phosphatase PTP1B and the dual specificity phosphatase KAP. These studies reveal that PTP1B and KAP utilize contrasting mechanisms in order to dephosphorylate their substrates specifically.

scholarly journals Differential sensitivity of the insulin-receptor kinase to thiol and oxidizing agents in the absence and presence of insulin

1987 ◽  
Vol 245 (2) ◽  
pp. 325-331 ◽  
Author(s):  
P A Wilden ◽  
J E Pessin
Keyword(s):  
Protein Kinase ◽  
Insulin Receptor ◽  
Kinase Activity ◽  
Beta Subunit ◽  
Differential Sensitivity ◽  
Protein Kinase Activity ◽  
Receptor Kinase ◽  
Nitrobenzoic Acid ◽  
Insulin Receptor Kinase ◽  
Receptor Beta

The purified human placental insulin-receptor beta-subunit autophosphorylating activity was found to be inhibited, in a time- and concentration-dependent manner, by the specific thiol-alkylating agents N-ethylmaleimide and 5,5′-dithiobis-(2-nitrobenzoic acid). The insulin-receptor kinase was observed to be more sensitive to inhibition by N-ethylmaleimide in the presence [IC50 (concn, giving 50% inhibition) = 25 +/- 3 microM] than in the absence (IC50 = 73 +/- 6 microM) of insulin. Similarly, inhibition by 5,5′-dithiobis-(2-nitrobenzoic acid) occurred with IC50 = 30 +/- 6 microM in the presence and 155 +/- 35 microM in the absence of insulin. Examination of the exogenous-substrate protein kinase activity demonstrated that the differential sensitivity to N-ethylmaleimide was due to direct inhibition of protein kinase activity, as opposed to blockade of the phospho-acceptor properties of the insulin receptor. In contrast, iodoacetamide had essentially no effect on the insulin-receptor beta-subunit autophosphorylating activity and was able to protect partially against the N-ethylmaleimide inhibition in both the presence and the absence of insulin. Consistent with these findings, none of the thiol-specific agents were able to alter significantly insulin binding at concentrations which maximally inhibited the beta-subunit autophosphorylation. Further, in the presence of insulin, the insulin-receptor kinase activity was also observed to be more sensitive to oxidation by H2O2 and FeCl3/ascorbate compared with insulin receptors in the absence of insulin. These results indicate that there is a critical thiol group(s) necessary for the beta-subunit autophosphorylating activity of the insulin-receptor kinase and that in the presence of insulin is more susceptible to exogenously added thiol and oxidizing agents.

scholarly journals Serine residues 994 and 1023/25 are important for insulin receptor kinase inhibition by protein kinase C isoforms β2 and θ

Diabetologia ◽  
2000 ◽  
Vol 43 (4) ◽  
pp. 443-449 ◽  
Author(s):  
V. Strack ◽  
A. M. Hennige ◽  
J. Krützfeldt ◽  
B. Bossenmaier ◽  
H. -H. Klein ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Insulin Receptor ◽  
Receptor Kinase ◽  
Kinase Inhibition ◽  
Kinase C ◽  
Insulin Receptor Kinase ◽  
Protein Kinase C Isoforms

scholarly journals Effect of basic polycations and proteins on purified insulin receptor. Insulin-independent activation of the receptor tyrosine-specific protein kinase by poly(l-lysine)

1989 ◽  
Vol 263 (3) ◽  
pp. 813-822 ◽  
Author(s):  
Y Fujita-Yamaguchi ◽  
D B Sacks ◽  
J M McDonald ◽  
D Sahal ◽  
S Kathuria
Keyword(s):  
Protein Kinase ◽  
Insulin Receptor ◽  
Kinase Activity ◽  
Specific Protein ◽  
Beta Subunit ◽  
Protein Kinase Activity ◽  
Receptor Kinase ◽  
Kinase Activation ◽  
Insulin Receptor Kinase ◽  
Specific Protein Kinase

Since the studies on tyrosine phosphorylation of calmodulin by the insulin receptor kinase in vitro suggested that protamine and poly(L-lysine) may activate phosphorylation of the receptor beta subunit [Sacks & McDonald (1988) J. Biol. Chem. 263, 2377-2383], we examined the effects of a variety of basic polycations/proteins and polyamines on insulin receptor kinase activity. The insulin receptor purified from human placental membranes was incubated with each basic polycation/protein or polyamine and assayed for tyrosine-specific protein kinase activity by measuring 32P incorporation into the src-related peptide. At a concentration of 1 microM, poly(L-lysine) and poly(L-ornithine) markedly stimulated kinase activity, whereas poly(L-arginine) and histones H1 and H2B inhibited insulin receptor kinase. In contrast, at a concentration of 1 mM, three polyamines (spermine, spermidine and putrescine) did not alter kinase activity. Poly(L-lysine) and poly(L-ornithine) stimulated the insulin receptor kinase by 5-10-fold at concentrations of 0.1-1 microM. Protamine sulphate also showed a significant stimulatory effect at a concentration of 100 microM. Preincubation of the receptor with poly(L-lysine) or poly(L-ornithine) for 20-60 min resulted in maximal kinase activation. Poly(L-lysine), the most effective activator of the receptor kinase, was used to characterize further the mechanisms of the kinase activation. Poly(L-lysine) activates the insulin receptor kinase by increasing the Vmax. without changing the Km. Poly(L-lysine) markedly stimulates the kinase activity of insulin receptor preparations that have lost both basal kinase activity and the ability to be stimulated by insulin. Insulin and poly(L-lysine) also differed in their ability to stimulate the kinase activity of prephosphorylated receptors. Prephosphorylation of the receptors did not affect the stimulation of the kinase by insulin. In contrast, prephosphorylation of receptors resulted in a markedly enhanced ability of poly(L-lysine) to stimulate kinase activity. These studies suggest that the mechanisms by which poly(L-lysine) and insulin activate the kinase are different. In conjunction with other additional evidence, it is suggested that poly(L-lysine) interacts directly with the beta-subunit of the receptor, thereby activating the receptor kinase.

Insulin-receptor kinase activity of adipose tissue from morbidly obese humans with and without NIDDM

Diabetes ◽  
1987 ◽  
Vol 36 (5) ◽  
pp. 620-625 ◽  
Author(s):  
M. K. Sinha ◽  
W. J. Pories ◽  
E. G. Flickinger ◽  
D. Meelheim ◽  
J. F. Caro
Keyword(s):  
Adipose Tissue ◽  
Insulin Receptor ◽  
Kinase Activity ◽  
Morbidly Obese ◽  
Receptor Kinase ◽  
Insulin Receptor Kinase ◽  
Insulin Receptor Kinase Activity

Alteration of insulin-receptor kinase activity by high-fat feeding

Diabetes ◽  
1988 ◽  
Vol 37 (10) ◽  
pp. 1397-1404 ◽  
Author(s):  
T. Watarai ◽  
M. Kobayashi ◽  
Y. Takata ◽  
T. Sasaoka ◽  
M. Iwasaki ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Kinase Activity ◽  
Receptor Kinase ◽  
High Fat ◽  
Insulin Receptor Kinase ◽  
Insulin Receptor Kinase Activity ◽  
Fat Feeding
Sign in / Sign up

Export Citation Format

Share Document