Cell Signaling by Tyrosine Phosphorylation: The Other Side of the Coin

1997 ◽  
pp. 107-112
Author(s):  
Edmond H. Fischer
Keyword(s):  
Cell Signaling ◽  
Tyrosine Phosphorylation ◽  
The Other

scholarly journals A Genetic Screen of the Drosophila X Chromosome for Mutations That Modify Deformed Function

Genetics ◽  
1998 ◽  
Vol 150 (4) ◽  
pp. 1497-1511 ◽  
Author(s):  
Brian Florence ◽  
William McGinnis
Keyword(s):  
Transcription Factor ◽  
Transcriptional Regulation ◽  
Cell Signaling ◽  
X Chromosome ◽  
Adaptor Protein ◽  
Genetic Screen ◽  
The Other ◽  
Homeotic Gene ◽  
Hox Proteins ◽  
Hox Gene

Abstract We have screened the Drosophila X chromosome for genes whose dosage affects the function of the homeotic gene Deformed. One of these genes, extradenticle, encodes a homeodomain transcription factor that heterodimerizes with Deformed and other homeotic Hox proteins. Mutations in the nejire gene, which encodes a transcriptional adaptor protein belonging to the CBP/p300 family, also interact with Deformed. The other previously characterized gene identified as a Deformed interactor is Notch, which encodes a transmembrane receptor. These three genes underscore the importance of transcriptional regulation and cell-cell signaling in Hox function. Four novel genes were also identified in the screen. One of these, rancor, is required for appropriate embryonic expression of Deformed and another homeotic gene, labial. Both Notch and nejire affect the function of another Hox gene, Ultrabithorax, indicating they may be required for homeotic activity in general.

Patterns of tyrosine phosphorylation differ in vascular hypertrophy and hyperplasia

1994 ◽  
Vol 267 (6) ◽  
pp. C1674-C1681 ◽  
Author(s):  
S. Ali ◽  
G. W. Dorn
Keyword(s):  
Smooth Muscle ◽  
Growth Factor ◽  
Tyrosine Phosphorylation ◽  
Growth Response ◽  
Thromboxane A2 ◽  
The Other ◽  
Platelet Derived Growth Factor ◽  
Phosphatidylinositol 3 Kinase ◽  
Gtpase Activating Protein ◽  
Herbimycin A

Vascular smooth muscle cells (VSMC) undergo hypertrophy when exposed to thromboxane A2 and hyperplasia when exposed to phorbol 12-myristate 13-acetate (PMA) or platelet-derived growth factor (PDGF). Each of these three agonists stimulate rapid tyrosine phosphorylation of numerous VSMC proteins. The current studies were undertaken to identify proteins that are specifically tyrosine phosphorylated in one or the other growth response. All three agonists increased the phosphotyrosine content of multiple proteins. In Western analysis of phosphotyrosine immunoprecipitates, the hyperplastic agents PDGF and PMA increased tyrosine phosphorylation of phospholipase C-gamma 1 (PLC-gamma 1), GTPase-activating protein (GAP), and phosphatidylinositol-3-kinase (PI-3-kinase), while the hypertrophic agonist thromboxane failed to tyrosine-phosphorylate either of these three substrates. Tyrosine kinase inhibition with herbimycin A (5 microM) prevented agonist-stimulated tyrosine phosphorylation of PLC-gamma 1, GAP, and PI-3-kinase. In growth studies, herbimycin A inhibited PMA- and PDGF-induced hyperplasia but not thromboxane-stimulated hypertrophy. These results indicate that tyrosine phosphorylation of PLC-gamma 1, GAP, and PI-3-kinase are specific responses for VSMC hyperplasia but not thromboxane-stimulated hypertrophy.

scholarly journals Regulation of hyperactivation by PPP2 in hamster spermatozoa

Reproduction ◽  
2010 ◽  
Vol 139 (5) ◽  
pp. 847-856 ◽  
Author(s):  
Tatsuya Suzuki ◽  
Masakatsu Fujinoki ◽  
Hiroaki Shibahara ◽  
Mitsuaki Suzuki
Keyword(s):  
Tyrosine Phosphorylation ◽  
Protein Phosphatases ◽  
Active Form ◽  
The Other ◽  
Other Hand ◽  
Inactive Form

It has been widely accepted that serine/threonine protein phosphatases (PPPs) are associated with the regulation of sperm hyperactivation. In the present study, we examined the types of PPPs associated with the regulation of hamster sperm hyperactivation. Protein phosphatases PPP1CA, PPP1CC, PPP2, and PPP3 are present in hamster sperm. In the experiments using several inhibitors, sperm hyperactivation was enhanced when PPP2 was inhibited at least, although inhibition of PPP1 also enhanced sperm hyperactivation. Interestingly, sperm were hyperactivated after PPP2 became an inactive form. And then, PPP1CA became an active form after sperm were hyperactivated. It has also been widely accepted that tyrosine phosphorylation is closely associated with the regulation of sperm hyperactivation. When PPP2 was inhibited, tyrosine phosphorylation was not enhanced at all. On the other hand, inhibition of PPP1 enhanced tyrosine phosphorylation. From the results, it is likely that PPP2 is closely associated with the regulation of sperm hyperactivation, although it is not associated with the regulation of tyrosine phosphorylation.

Palmitoylation of prohibitin at cysteine 69 facilitates its membrane translocation and interaction with Eps 15 homology domain protein 2 (EHD2)

2010 ◽  
Vol 88 (3) ◽  
pp. 553-558 ◽  
Author(s):  
Sudharsana Rao Ande ◽  
Suresh Mishra
Keyword(s):  
Plasma Membrane ◽  
Cell Signaling ◽  
Signaling Pathways ◽  
Tyrosine Phosphorylation ◽  
Lipid Raft ◽  
Plasma Membranes ◽  
Cell Types ◽  
Membrane Translocation ◽  
Domain Protein ◽  
Cell Signaling Pathways

Plasma membrane translocation of specific cytosolic proteins plays an important role in cell signaling pathways. We have recently shown that prohibitin (PHB) , a protein present in the plasma membranes of various cell types, interacts with Eps 15 homology domain protein 2 (EHD2), a lipid raft protein. However, the mechanism involved in membrane translocation of PHB is not known.We report that PHB undergoes palmitoylation at cysteine 69 (Cys69), and that this palmitoylation is required for PHB's membrane translocation. Furthermore, we demonstrate that membrane translocation of PHB facilitates tyrosine phosphorylation and its interaction with EHD2. Thus, the palmitoylation and membrane translocation of PHB and its interaction with EHD2 may play a role in cell signaling.

scholarly journals Identification of the tyrosine phosphatase PTP1C as a B cell antigen receptor-associated protein involved in the regulation of B cell signaling.

1995 ◽  
Vol 181 (6) ◽  
pp. 2077-2084 ◽  
Author(s):  
G Pani ◽  
M Kozlowski ◽  
J C Cambier ◽  
G B Mills ◽  
K A Siminovitch
Keyword(s):  
B Cells ◽  
Cell Signaling ◽  
B Cell ◽  
Phosphatase Activity ◽  
Tyrosine Phosphorylation ◽  
Tyrosine Phosphatase ◽  
Cross Linking ◽  
B Cell Antigen Receptor ◽  
Wild Type ◽  
B Cell Signaling

Recent data implicating loss of PTP1C tyrosine phosphatase activity in the genesis of the multiple hemopoietic cell defects found in systemic autoimmune/immunodeficient motheaten (me) and viable motheaten (mev) mice suggest that PTP1C plays an important role in modulating intracellular signaling events regulating cell activation and differentiation. To begin elucidating the role for this cytosolic phosphatase in lymphoid cell signal transduction, we have examined early signaling events and mitogenic responses induced by B cell antigen receptor (BCR) ligation in me and mev splenic B cells and in CD5+ CH12 lymphoma cells, which represent the lymphoid population amplified in motheaten mice. Despite their lack of functional PTP1C, me and mev B cells proliferated normally in response to LPS. However, compared with wild-type B cells, cells from the mutant mice were hyperresponsive to normally submitogenic concentrations of F(ab')2 anti-Ig antibody, and they exhibited reduced susceptibility to the inhibitory effects of Fc gamma IIRB cross-linking on BCR-induced proliferation. Additional studies of unstimulated CH12 and wild-type splenic B cells revealed the constitutive association of PTP1C with the resting BCR complex, as evidenced by coprecipitation of PTP1C protein and phosphatase activity with BCR components and the depletion of BCR-associated tyrosine phosphatase activity by anti-PTP1C antibodies. These results suggest a role for PTP1C in regulating the tyrosine phosphorylation state of the resting BCR complex components, a hypothesis supported by the observation that PTP1C specifically induces dephosphorylation of a 35-kD BCR-associated protein likely representing Ig-alpha. In contrast, whereas membrane Ig cross-linking was associated with an increase in the tyrosine phosphorylation of PTP1C and an approximately 140-kD coprecipitated protein, PTP1C was no longer detected in the BCR complex after receptor engagement, suggesting that PTP1C dissociates from the activated receptor complex. Together these results suggest a critical role for PTP1C in modulating BCR signaling capacity, and they indicate that the PTP1C influence on B cell signaling is likely to be realized in both resting and activated cells.

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