scholarly journals Tyrosine phosphorylation and stimulation of protein kinase Cδ from porcine spleen by src in vitro

FEBS Letters ◽  
1994 ◽  
Vol 347 (1) ◽  
pp. 85-89 ◽  
Author(s):  
Michael Gschwendt ◽  
Kirsten Kielbassa ◽  
Walter Kittstein ◽  
Friedrich Marks
Keyword(s):  
Protein Kinase ◽  
Tyrosine Phosphorylation ◽  
Stimulation Of ◽  
Protein Kinase Cδ

scholarly journals The pathophysiologic role of the protein kinase Cδ pathway in the intervertebral discs of rabbits and mice: In vitro, ex vivo, and in vivo studies

2012 ◽  
Vol 64 (6) ◽  
pp. 1950-1959 ◽  
Author(s):  
Michael B. Ellman ◽  
Jae-Sung Kim ◽  
Howard S. An ◽  
Jeffrey S. Kroin ◽  
Xin Li ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Ex Vivo ◽  
Intervertebral Discs ◽  
In Vivo Studies ◽  
Protein Kinase Cδ

Structural and functional modification of pp60c-src associated with polyoma middle tumor antigen from infected or transformed cells

1985 ◽  
Vol 5 (10) ◽  
pp. 2647-2652
Author(s):  
C A Cartwright ◽  
M A Hutchinson ◽  
W Eckhart
Keyword(s):  
Protein Kinase ◽  
Tyrosine Phosphorylation ◽  
Tumor Antigen ◽  
Kinase Activity ◽  
Protein Kinase Activity ◽  
Amino Terminal ◽  
Exogenous Substrate ◽  
And Function ◽  
Amino Terminal Domain

The polyoma middle tumor antigen (MTAg) associates with the src proto-oncogene product pp60c-src in infected or transformed rodent cells. The tyrosine protein kinase activity of pp60c-src, as measured by in vitro phosphorylation of pp60c-src itself or the exogenous substrate enolase, was increased 10- to 20-fold in cells transformed or infected with transformation-competent polyoma virus compared with controls. pp60c-src associated with MTAg and precipitated with polyoma antitumor serum had a novel site(s) of in vitro tyrosine phosphorylation within its amino-terminal domain. These observations suggest that association of MTAg with pp60c-src alters the accessibility of pp60c-src tyrosine residues for phosphorylation in vitro and increases pp60c-src protein kinase activity. Several transformation-defective mutants of MTAg did not cause amino-terminal tyrosine phosphorylation of pp60c-src in vitro or enhance its protein kinase activity, suggesting that these properties correlate with the transforming ability of MTAg. However, one transformation-defective MTAg mutant, dl1015, did cause amino-terminal tyrosine phosphorylation of pp60c-src in vitro and did enhance its protein kinase activity. This suggests that properties of MTAg, in addition to modifying the structure and function of pp60c-src, may be important for transformation.

scholarly journals Modification of the 85-kilodalton subunit of phosphatidylinositol-3 kinase in platelet-derived growth factor-stimulated cells.

1992 ◽  
Vol 12 (8) ◽  
pp. 3415-3424 ◽  
Author(s):  
W M Kavanaugh ◽  
A Klippel ◽  
J A Escobedo ◽  
L T Williams
Keyword(s):  
Tyrosine Phosphorylation ◽  
Platelet Derived Growth Factor ◽  
Affinity Binding ◽  
Pdgf Receptor ◽  
Phosphatidylinositol 3 Kinase ◽  
High Affinity Binding ◽  
High Affinity ◽  
Pdgf Stimulation ◽  
Stimulation Of

The activated platelet-derived growth factor (PDGF) receptor physically associates with p85, a subunit of phosphatidylinositol-3 kinase. Although this interaction may activate phosphatidylinositol-kinase and is crucial for PDGF-induced mitogenesis, it has not been shown whether p85 is modified in the process. p85 contains two SH2 (Src homology) domains, designated SH2-N and SH2-C. Recent experiments have shown that the SH2-C domain alone determines high-affinity binding of p85 to the PDGF receptor. The function of SH2-N, which binds receptors with lower affinity, is unknown. In this study, using a receptor-blotting technique, we find that p85 is modified by PDGF stimulation of intact cells. This modification involves inhibition of binding of the SH2-N region of p85 to the PDGF receptor. Studies with vanadate suggest that tyrosine phosphorylation of p85 is responsible for the modification of p85 detected by receptor blotting. Furthermore, recombinant p85 is modified in a similar manner when it is tyrosine phosphorylated in vitro by PDGF receptors. Tyrosine phosphorylation of p85 does not block binding of the SH2-C domain and therefore does not release p85 from high-affinity binding sites on the receptor in vitro. Instead, phosphorylation may regulate the ability of the SH2-N of p85 to bind to a different portion of the PDGF receptor or to another molecule in the signaling complex. This study provides the first evidence that p85 is tyrosine phosphorylated upon PDGF stimulation of cells and suggests that tyrosine phosphorylation of p85 regulates its activity or its interaction with other proteins.

Mitogen stimulation of Na+-H+ exchange: differential involvement of protein kinase C

1987 ◽  
Vol 253 (2) ◽  
pp. C219-C229 ◽  
Author(s):  
L. L. Muldoon ◽  
G. A. Jamieson ◽  
A. C. Kao ◽  
H. C. Palfrey ◽  
M. L. Villereal
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cell Types ◽  
Intact Cells ◽  
Kinase C ◽  
Protein Kinase C Activity ◽  
Human Fibroblast Strains ◽  
Stimulation Of

The mitogen-induced activation of Na+-H+ exchange was investigated in two cultured human fibroblast strains (HSWP and WI-38 cells) that, based on previous studies, differed in their response to the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) (L. M. Vincentini and M. L. Villereal, Proc. Natl. Acad. Sci. USA 82: 8053-8056, 1985). The role of protein kinase C in the activation of Na+-H+ exchange was investigated by comparing the effects of TPA on Na+ influx, in vitro phosphorylation, and in vivo phosphorylation in both cell types. Although both cell types have significant quantities of protein kinase C activity that can be activated by TPA in intact cells, the addition of TPA to intact cells stimulates Na+ influx in WI-38 cells but not in HSWP cells, indicating that in HSWP cells the stimulation of protein kinase C is not sufficient to activate the Na+-H+ exchanger. Cells were then depleted of protein kinase C activity by chronic treatment with high doses of TPA. Both HSWP and WI-38 cells were rendered protein kinase C deficient by this treatment as determined by in vitro and in vivo phosphorylation studies. Protein kinase C-deficient HSWP cells lose the ability for TPA to inhibit the serum-induced activation of Na+-H+ exchange, but there is no reduction in the stimulation of Na+ influx by serum, bradykinin, vasopressin, melittin, or vanadate, indicating that protein kinase C activity is not necessary for the mitogen-induced activation of Na+-H+ exchange in HSWP cells by agents known to stimulate phosphatidylinositol turnover (G. A. Jamieson and M. Villereal. Arch. Biochem. Biophys. 252: 478-486, 1987). In contrast, depletion of protein kinase C activity in WI-38 cells significantly reduces both the TPA- and the serum-induced activation of the Na+-H+ exchange system, suggesting that protein kinase C activity is necessary for at least a portion of the mitogen-induced activation of the Na+-H+ exchanger in WI-38 cells. These results indicate that the mechanisms for regulating Na+-H+ exchange can differ dramatically between different types of fibroblasts.

scholarly journals Tyrosine 425 within the activated erythropoietin receptor binds Syp, reduces the erythropoietin required for Syp tyrosine phosphorylation, and promotes mitogenesis

Blood ◽  
1996 ◽  
Vol 87 (11) ◽  
pp. 4495-4501 ◽  
Author(s):  
T Tauchi ◽  
JE Damen ◽  
K Toyama ◽  
GS Feng ◽  
HE Broxmeyer ◽  
...  
Keyword(s):  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Intracellular Signaling ◽  
Tyrosine Phosphatase ◽  
Erythropoietin Receptor ◽  
Sh2 Domains ◽  
Proliferation And Differentiation ◽  
Stimulation Of

Erythropoietin (Epo), the primary in vivo stimulator of erythroid proliferation and differentiation, acts, in part, by altering the tyrosine phosphorylation levels of various intracellular signaling molecules. These phosphorylation levels are tightly regulated by both tyrosine kinases and tyrosine phosphatases. We have recently shown that the SH2 containing tyrosine phosphatase, Syp, binds directly to both the tyrosine phosphorylated form of the Epo receptor (EpoR) and to Grb2 after Epo stimulation of M07e cells engineered to express high levels of human EpoRs (T. Tauchi, et al: J Biol Chem 270:5631, 1995). To determine which tyrosine within the EpoR is responsible for binding Syp, we examined DA-3 cell lines expressing full-length mutant EpoRs bearing tyrosine to phenylalanine substitutions for each of the eight tyrosines within the intracellular domain of the EpoR. We found that: (1) all Epo-stimulated mutant EpoRs, except for the Y425F EpoR, coimmunoprecipitated with Syp; (2) all Epo-stimulated mutant EpoRs, except for the Y425F EpoR, bound to a GST-fusion protein containing both SH2 domains of Syp; (3) Jak2 could phosphorylate GST-Syp in vitro after Epo stimulation of wild-type (wt) EpoR expressing DA-3 cells; (4) Epo-stimulated tyrosine phosphorylation of Syp in vivo was markedly reduced in Y425F EpoR expressing DA-3 calls; and (5) DA-3 cells expressing the Y425F EpoR grow less well in response to Epo than wt EpoR expressing cells. These results suggest that Syp binds via its SH2 domains to phosphorylated Y425 within the EpoR and is then phosphorylated on tyrosine residues by Jak2. Moreover, Y425 in the EpoR reduces the Epo requirement for Syp tyrosine phosphorylation and promotes proliferation.

scholarly journals Regulation of 3-Phosphoinositide-dependent Protein Kinase-1 (PDK1) by Src Involves Tyrosine Phosphorylation of PDK1 and Src Homology 2 Domain Binding

2007 ◽  
Vol 283 (3) ◽  
pp. 1480-1491 ◽  
Author(s):  
Keum-Jin Yang ◽  
Sanghee Shin ◽  
Longzhen Piao ◽  
Eulsoon Shin ◽  
Yuwen Li ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Complex Formation ◽  
Tyrosine Phosphorylation ◽  
Immunohistochemical Analysis ◽  
Sh2 Domain ◽  
Resting Cells ◽  
Dependent Protein Kinase ◽  
Hek 293 ◽  
Dependent Protein

3-Phosphoinositide-dependent protein kinase-1 (PDK1) appears to play a central regulatory role in many cell signalings between phosphoinositide-3 kinase and various intracellular serine/threonine kinases. In resting cells, PDK1 is known to be constitutively active and is further activated by tyrosine phosphorylation (Tyr9 and Tyr373/376) following the treatment of the cell with insulin or pervanadate. However, little is known about the mechanisms for this additional activation of PDK1. Here, we report that the SH2 domain of Src, Crk, and GAP recognized tyrosine-phosphorylated PDK1 in vitro. Destabilization of PDK1 induced by geldanamycin (a Hsp90 inhibitor) was partially blocked in HEK 293 cells expressing PDK1-Y9F. Co-expression of Hsp90 enhanced PDK1-Src complex formation and led to further increased PDK1 activity toward PKB and SGK. Immunohistochemical analysis with anti-phospho-Tyr9 antibodies showed that the level of Tyr9 phosphorylation was markedly increased in tumor samples compared with normal. Taken together, these data suggest that phosphorylation of PDK1 on Tyr9, distinct from Tyr373/376, is important for PDK1/Src complex formation, leading to PDK1 activation. Furthermore, Tyr9 phosphorylation is critical for the stabilization of both PDK1 and the PDK1/Src complex via Hsp90-mediated protection of PDK1 degradation.

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