scholarly journals Identification of Csk tyrosine phosphorylation sites and a tyrosine residue important for kinase domain structure

1997 ◽  
Vol 322 (3) ◽  
pp. 927-935 ◽  
Author(s):  
Vladimir JOUKOV ◽  
Mauno VIHINEN ◽  
Satu VAINIKKA ◽  
Janusz M. SOWADSKI ◽  
Kari ALITALO ◽  
...  

The lack of a conserved tyrosine autophosphorylation site is a unique feature of the C-terminal Src-kinase, Csk, although this protein tyrosine kinase can be autophosphorylated on tyrosine residues in vitro and in bacteria. Here we show that human Csk is tyrosine phosphorylated in HeLa cells treated with sodium pervanadate. Phosphorylation in vivo occurs mainly at Tyr-184 and in vitro mainly at Tyr-304. A Y304F mutation strongly decreased Csk phosphorylation in vitro, and a Y184F mutation abolished tyrosine phosphorylation in vivo. A catalytically inactive form of Csk was also phosphorylated on Tyr-184 in vivo, suggesting that this is not a site of autophosphorylation. The kinase activity of the Y184F protein was not changed, while the Y304F protein showed one-third of wild-type activity. Three-dimensional modelling of the Csk kinase domain indicated that the Y304F mutation abolishes one of two conserved hydrogen bonds between the upper and the lower lobes in the open conformation of the kinase domain. Phosphopeptide binding studies suggested that phosphorylation of Tyr-184 creates a binding site for low-molecular-mass proteins. Cellular Csk was associated with several phosphoproteins, some of which were interacting with the Csk SH2 domain. Taken together these results indicate that Csk can be phosphorylated in vivo at Tyr-184 by an as yet unknown tyrosine kinase, and that autophosphorylation of Tyr-304 occurs only at abnormally high Csk concentrations in vitro. Furthermore, Tyr-304 is required for the maintenance of the structure of the Csk kinase domain.

Blood ◽  
1998 ◽  
Vol 91 (10) ◽  
pp. 3734-3745 ◽  
Author(s):  
Hiroshi Chin ◽  
Ayako Arai ◽  
Hiroshi Wakao ◽  
Ryuichi Kamiyama ◽  
Nobuyuki Miyasaka ◽  
...  

Abstract Protein tyrosine phosphorylation plays a crucial role in signaling from the receptor for erythropoietin (Epo), although the Epo receptor (EpoR) lacks the tyrosine kinase domain. We have previously shown that the Jak2 tyrosine kinase couples with the EpoR to transduce a growth signal. In the present study, we demonstrate that Lyn, a Src family tyrosine kinase, physically associates with the EpoR in Epo-dependent hematopoietic cell lines, 32D/EpoR-Wt and F36E. Coexpression experiments in COS7 cells further showed that Lyn induces tyrosine phosphorylation of the EpoR and that both LynA and LynB, alternatively spliced forms of Lyn, bind with the membrane-proximal 91-amino acid region of the EpoR cytoplasmic domain. In vitro binding studies using GST-Lyn fusion proteins further showed that the Src homology (SH)-2 domain of Lyn specifically binds with the tyrosine-phosphorylated EpoR in lysate from Epo-stimulated cells, whereas the tyrosine kinase domain of Lyn binds with the unphosphorylated EpoR. Far-Western blotting and synthetic phosphopeptide competition assays further indicated that the Lyn SH2 domain directly binds to the tyrosine-phosphorylated EpoR, most likely through its interaction with phosphorylated Y-464 or Y-479 in the carboxy-terminal region of the EpoR. In vitro binding studies also demonstrated that the Lyn SH2 domain directly binds to tyrosine-phosphorylated Jak2. In vitro reconstitution experiments in COS7 cells further showed that Lyn induces tyrosine phosphorylation of Stat5, mainly on Y-694, and activates the DNA-binding and transcription-activating abilities of Stat5. In agreement with this, Lyn enhanced the Stat5-dependent transcriptional activation when overexpressed in 32D/EpoR-Wt cells. In addition, Lyn was demonstrated to phosphorylate the EpoR and Stat5 on tyrosines in vitro. These results suggest that Lyn may play a role in activation of the Jak2/Stat5 and other signaling pathways by the EpoR.


Blood ◽  
1998 ◽  
Vol 91 (10) ◽  
pp. 3734-3745 ◽  
Author(s):  
Hiroshi Chin ◽  
Ayako Arai ◽  
Hiroshi Wakao ◽  
Ryuichi Kamiyama ◽  
Nobuyuki Miyasaka ◽  
...  

Protein tyrosine phosphorylation plays a crucial role in signaling from the receptor for erythropoietin (Epo), although the Epo receptor (EpoR) lacks the tyrosine kinase domain. We have previously shown that the Jak2 tyrosine kinase couples with the EpoR to transduce a growth signal. In the present study, we demonstrate that Lyn, a Src family tyrosine kinase, physically associates with the EpoR in Epo-dependent hematopoietic cell lines, 32D/EpoR-Wt and F36E. Coexpression experiments in COS7 cells further showed that Lyn induces tyrosine phosphorylation of the EpoR and that both LynA and LynB, alternatively spliced forms of Lyn, bind with the membrane-proximal 91-amino acid region of the EpoR cytoplasmic domain. In vitro binding studies using GST-Lyn fusion proteins further showed that the Src homology (SH)-2 domain of Lyn specifically binds with the tyrosine-phosphorylated EpoR in lysate from Epo-stimulated cells, whereas the tyrosine kinase domain of Lyn binds with the unphosphorylated EpoR. Far-Western blotting and synthetic phosphopeptide competition assays further indicated that the Lyn SH2 domain directly binds to the tyrosine-phosphorylated EpoR, most likely through its interaction with phosphorylated Y-464 or Y-479 in the carboxy-terminal region of the EpoR. In vitro binding studies also demonstrated that the Lyn SH2 domain directly binds to tyrosine-phosphorylated Jak2. In vitro reconstitution experiments in COS7 cells further showed that Lyn induces tyrosine phosphorylation of Stat5, mainly on Y-694, and activates the DNA-binding and transcription-activating abilities of Stat5. In agreement with this, Lyn enhanced the Stat5-dependent transcriptional activation when overexpressed in 32D/EpoR-Wt cells. In addition, Lyn was demonstrated to phosphorylate the EpoR and Stat5 on tyrosines in vitro. These results suggest that Lyn may play a role in activation of the Jak2/Stat5 and other signaling pathways by the EpoR.


Blood ◽  
1996 ◽  
Vol 88 (12) ◽  
pp. 4415-4425 ◽  
Author(s):  
H Chin ◽  
N Nakamura ◽  
R Kamiyama ◽  
N Miyasaka ◽  
JN Ihle ◽  
...  

Erythropoietin (Epo) and interleukin-3 (IL-3) stimulate activation of the Jak2 tyrosine kinase and induce tyrosine phosphorylation and activation of Stat5. In the present study, we have shown that Epo or IL-3 stimulation induces binding of Stat5 to the tyrosine-phosphorylated Epo receptor (EpoR) or IL-3 receptor beta subunit (betaIL3), respectively, in IL-3-dependent 32D cells expressing the EpoR. The binding of Stat5 to these cytokine receptors was shown to be rapid and transient, occurring within 1 minute of stimulation of cells and significantly decreasing after 5 minutes of cell treatment. In vivo binding experiments in COS cells showed that binding of Stat5 to the EpoR was mediated through the Stat5 Src homology 2 (SH2) domain. In vitro binding studies further showed that Stat5, but not other Stats examined, bound specifically to tyrosine-phosphorylated recombinant EpoR fusion proteins. In these in vivo and in vitro binding studies, Stat5 bound, albeit to a lesser degree, to truncated EpoR mutants in which all the intracellular tyrosines except Y-343 were removed. Furthermore, EpoR-derived synthetic phosphotyrosine peptides corresponding to Y-343, Y-401, Y-431, and Y-479 inhibited the in vitro binding of Stat5. When expressed in 32D cells, a mutant EpoR in which all the intracellular tyrosines were removed by carboxy-terminal truncation showed a significantly impaired ability to induce tyrosine phosphorylation of Stat5, particularly at low concentrations of Epo, but exhibited an increased sensitivity to Epo for growth signaling as compared with the wild-type EpoR. These results indicate that Stat5 specifically and transiently binds to the EpoR through the interaction between the Stat5 SH2 domain and specific phosphorylated tyrosines, including Y-343, in the EpoR cytoplasmic domain. It was implied that betaIL3 may also have similar Stat5 docking sites. The Stat5 docking sites in the EpoR were shown to facilitate specific activation of Stat5, which, however, may not be required for the EpoR-mediated growth signaling.


2004 ◽  
Vol 24 (21) ◽  
pp. 9351-9358 ◽  
Author(s):  
Charles E. Laurent ◽  
Frank J. Delfino ◽  
Haiyun Y. Cheng ◽  
Thomas E. Smithgall

ABSTRACT The c-Fes protein-tyrosine kinase (Fes) has been implicated in the differentiation of vascular endothelial, myeloid hematopoietic, and neuronal cells, promoting substantial morphological changes in these cell types. The mechanism by which Fes promotes morphological aspects of cellular differentiation is unknown. Using COS-7 cells as a model system, we observed that Fes strongly colocalizes with microtubules in vivo when activated via coiled-coil mutation or by coexpression with an active Src family kinase. In contrast, wild-type Fes showed a diffuse cytoplasmic localization in this system, which correlated with undetectable kinase activity. Coimmunoprecipitation and immunofluorescence microscopy showed that the N-terminal Fes/CIP4 homology (FCH) domain is involved in Fes interaction with soluble unpolymerized tubulin. However, the FCH domain was not required for colocalization with polymerized microtubules in vivo. In contrast, a functional SH2 domain was essential for microtubule localization of Fes, consistent with the strong tyrosine phosphorylation of purified tubulin by Fes in vitro. Using a microtubule nucleation assay, we observed that purified c-Fes also catalyzed extensive tubulin polymerization in vitro. Taken together, these results identify c-Fes as a regulator of the tubulin cytoskeleton that may contribute to Fes-induced morphological changes in myeloid hematopoietic and neuronal cells.


1995 ◽  
Vol 15 (2) ◽  
pp. 835-842 ◽  
Author(s):  
Y Maru ◽  
K L Peters ◽  
D E Afar ◽  
M Shibuya ◽  
O N Witte ◽  
...  

The human bcr gene encodes a protein with serine/threonine kinase activity, CDC24/dbl homology, a GAP domain, and an SH2-binding region. However, the precise physiological functions of BCR are unknown. Coexpression of BCR with the cytoplasmic protein-tyrosine kinase encoded by the c-fes proto-oncogene in Sf-9 cells resulted in stable BCR-FES protein complex formation and tyrosine phosphorylation of BCR. Association involves the SH2 domain of FES and a novel binding domain localized to the first 347 amino acids of the FES N-terminal region. Deletion of the homologous N-terminal BCR-binding domain from v-fps, a fes-related transforming oncogene, abolished transforming activity and tyrosine phosphorylation of BCR in vivo. Tyrosine phosphorylation of BCR in v-fps-transformed cells induced its association with GRB-2/SOS, the RAS guanine nucleotide exchange factor complex. These data provide evidence that BCR couples the cytoplasmic protein-tyrosine kinase and RAS signaling pathways.


1992 ◽  
Vol 12 (3) ◽  
pp. 1366-1374 ◽  
Author(s):  
C A Koch ◽  
M F Moran ◽  
D Anderson ◽  
X Q Liu ◽  
G Mbamalu ◽  
...  

The Src homology 2 (SH2) domain is a noncatalytic region which is conserved among a number of signaling and transforming proteins, including cytoplasmic protein-tyrosine kinases and Ras GTPase-activating protein (GAP). Genetic and biochemical data indicate that the SH2 domain of the p60v-src (v-Src) protein-tyrosine kinase is required for full v-src transforming activity and may direct the association of v-Src with specific tyrosine-phosphorylated proteins. To test the ability of the v-Src SH2 domain to mediate protein-protein interactions, v-Src polypeptides were expressed as fusion proteins in Escherichia coli. The bacterial v-Src SH2 domain bound a series of tyrosine-phosphorylated proteins in a lysate of v-src-transformed Rat-2 cells, including prominent species of 130 and 62 kDa (p130 and p62). The p130 and p62 tyrosine-phosphorylated proteins that complexed v-Src SH2 in vitro also associated with v-Src in v-src-transformed Rat-2 cells; this in vivo binding was dependent on the v-Src SH2 domain. In addition to binding soluble p62 and p130, the SH2 domains of v-Src, GAP, and v-Crk directly recognized these phosphotyrosine-containing proteins which had been previously denatured and immobilized on a filter. In addition, the SH2 domains of GAP and v-Crk bound to the GAP-associated protein p190 immobilized on a nitrocellulose membrane. These results show that SH2 domains bind directly to tyrosine-phosphorylated proteins and that the Src SH2 domain can bind phosphorylated targets of the v-Src kinase domain.(ABSTRACT TRUNCATED AT 250 WORDS)


1992 ◽  
Vol 12 (3) ◽  
pp. 1366-1374
Author(s):  
C A Koch ◽  
M F Moran ◽  
D Anderson ◽  
X Q Liu ◽  
G Mbamalu ◽  
...  

The Src homology 2 (SH2) domain is a noncatalytic region which is conserved among a number of signaling and transforming proteins, including cytoplasmic protein-tyrosine kinases and Ras GTPase-activating protein (GAP). Genetic and biochemical data indicate that the SH2 domain of the p60v-src (v-Src) protein-tyrosine kinase is required for full v-src transforming activity and may direct the association of v-Src with specific tyrosine-phosphorylated proteins. To test the ability of the v-Src SH2 domain to mediate protein-protein interactions, v-Src polypeptides were expressed as fusion proteins in Escherichia coli. The bacterial v-Src SH2 domain bound a series of tyrosine-phosphorylated proteins in a lysate of v-src-transformed Rat-2 cells, including prominent species of 130 and 62 kDa (p130 and p62). The p130 and p62 tyrosine-phosphorylated proteins that complexed v-Src SH2 in vitro also associated with v-Src in v-src-transformed Rat-2 cells; this in vivo binding was dependent on the v-Src SH2 domain. In addition to binding soluble p62 and p130, the SH2 domains of v-Src, GAP, and v-Crk directly recognized these phosphotyrosine-containing proteins which had been previously denatured and immobilized on a filter. In addition, the SH2 domains of GAP and v-Crk bound to the GAP-associated protein p190 immobilized on a nitrocellulose membrane. These results show that SH2 domains bind directly to tyrosine-phosphorylated proteins and that the Src SH2 domain can bind phosphorylated targets of the v-Src kinase domain.(ABSTRACT TRUNCATED AT 250 WORDS)


1992 ◽  
Vol 12 (10) ◽  
pp. 4706-4713
Author(s):  
H Sabe ◽  
M Okada ◽  
H Nakagawa ◽  
H Hanafusa

The protein product of the CT10 virus, p47gag-crk (v-Crk), which contains Src homology region 2 (SH2) and 3 (SH3) domains but lacks a kinase domain, is believed to cause an increase in cellular protein tyrosine phosphorylation. A candidate tyrosine kinase, Csk (C-terminal Src kinase), has been implicated in c-Src Tyr-527 phosphorylation, which negatively regulates the protein tyrosine kinase of pp60c-src (c-Src). To investigate how c-Src kinase activity is regulated in vivo, we first looked at whether v-Crk can activate c-Src kinase. We found that cooverexpression of v-Crk and c-Src caused elevation of c-Src kinase activity, resulting in an increase of tyrosine phosphorylation of cellular proteins and morphological transformation of rat 3Y1 fibroblasts. v-Crk and c-Src complexes were not detected, although v-Crk bound to a variety of tyrosine-phosphorylated proteins in cells overexpressing v-Crk and c-Src. Overexpression of Csk in these transformed cells caused reversion to normal phenotypes and also reduced the level of c-Src kinase activity. However, Csk did not cause reversion of cells transformed by v-Src or c-Src527F, in which Tyr-527 was changed to Phe. These results strongly suggest that Csk acts on Tyr-527 of c-Src and suppresses c-Src kinase activity in vivo. Because Csk can suppress transformation by cooverexpression of v-Crk and c-Src, we suggest that v-Crk causes activation of c-Src in vivo by altering the phosphorylation state of Tyr-527.


1997 ◽  
Vol 17 (3) ◽  
pp. 1702-1713 ◽  
Author(s):  
D D Schlaepfer ◽  
M A Broome ◽  
T Hunter

The focal adhesion kinase (FAK), a protein-tyrosine kinase (PTK), associates with integrin receptors and is activated by cell binding to extracellular matrix proteins, such as fibronectin (FN). FAK autophosphorylation at Tyr-397 promotes Src homology 2 (SH2) domain binding of Src family PTKs, and c-Src phosphorylation of FAK at Tyr-925 creates an SH2 binding site for the Grb2 SH2-SH3 adaptor protein. FN-stimulated Grb2 binding to FAK may facilitate intracellular signaling to targets such as ERK2-mitogen-activated protein kinase. We examined FN-stimulated signaling to ERK2 and found that ERK2 activation was reduced 10-fold in Src- fibroblasts, compared to that of Src- fibroblasts stably reexpressing wild-type c-Src. FN-stimulated FAK phosphotyrosine (P.Tyr) and Grb2 binding to FAK were reduced, whereas the tyrosine phosphorylation of another signaling protein, p130cas, was not detected in the Src- cells. Stable expression of residues 1 to 298 of Src (Src 1-298, which encompass the SH3 and SH2 domains of c-Src) in the Src- cells blocked Grb2 binding to FAK; but surprisingly, Src 1-298 expression also resulted in elevated p130cas P.Tyr levels and a two- to threefold increase in FN-stimulated ERK2 activity compared to levels in Src- cells. Src 1-298 bound to both FAK and p130cas and promoted FAK association with p130cas in vivo. FAK was observed to phosphorylate p130cas in vitro and could thus phosphorylate p130cas upon FN stimulation of the Src 1-298-expressing cells. FAK-induced phosphorylation of p130cas in the Src 1-298 cells promoted the SH2 domain-dependent binding of the Nck adaptor protein to p130cas, which may facilitate signaling to ERK2. These results show that there are additional FN-stimulated pathways to ERK2 that do not involve Grb2 binding to FAK.


2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Matthias Kästle ◽  
Camilla Merten ◽  
Roland Hartig ◽  
Thilo Kaehne ◽  
Ardiyanto Liaunardy-Jopeace ◽  
...  

Abstract Background Upon engagement of the T-cell receptor (TCR), the Src-family protein tyrosine kinase p56Lck phosphorylates components of the TCR (e.g. the TCRζ chains), thereby initiating T-cell activation. The enzymatic activity of Lck is primarily regulated via reversible and dynamic phosphorylation of two tyrosine residues, Y394 and Y505. Lck possesses an additional highly conserved tyrosine Y192, located within the SH2 domain, whose role in T-cell activation is not fully understood. Methods Knock-in mice expressing a phospho-mimetic (Y192E) form of Lck were generated. Cellular and biochemical characterization was performed to elucidate the function of Y192 in primary T cells. HEK 293T and Jurkat T cells were used for in vitro studies. Results Co-immunoprecipitation studies and biochemical analyses using T cells from LckY192E knock-in mice revealed a diminished binding of LckY192E to CD45 and a concomitant hyperphosphorylation of Y505, thus corroborating previous data obtained in Jurkat T cells. Surprisingly however, in vitro kinase assays showed that LckY192E possesses a normal enzymatic activity in human and murine T cells. FLIM/FRET measurements employing an LckY192E biosensor further indicated that the steady state conformation of the LckY192E mutant is similar to Lckwt. These data suggest that Y192 might regulate Lck functions also independently from the Lck/CD45-association. Indeed, when LckY192E was expressed in CD45−/−/Csk−/− non-T cells (HEK 293T cells), phosphorylation of Y505 was similar to Lckwt, but LckY192E still failed to optimally phosphorylate and activate the Lck downstream substrate ZAP70. Furthermore, LckY19E was recruited less to CD3 after TCR stimulation. Conclusions Taken together, phosphorylation of Y192 regulates Lck functions in T cells at least twofold, by preventing Lck association to CD45 and by modulating ligand-induced recruitment of Lck to the TCR. Major findings Our data change the current view on the function of Y192 and suggest that Y192 also regulates Lck activity in a manner independent of Y505 phosphorylation.


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