scholarly journals Identification of a novel autophosphorylation site (P4) on the epidermal growth factor receptor

1989 ◽  
Vol 262 (2) ◽  
pp. 659-663 ◽  
Author(s):  
J J Hsuan ◽  
N Totty ◽  
M D Waterfield
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Tryptic Peptide ◽  
Growth Factor Receptor ◽  
Intact Cells ◽  
C Terminus ◽  
Partial Digestion ◽  
Epidermal Growth ◽  
Autophosphorylation Site

Three major autophosphorylation sites are located near the C-terminus of the epidermal growth factor receptor, but a fourth site is repeatedly detected. We report here the purification and sequencing of a tryptic peptide containing this site, Tyr-1086. Furthermore, we demonstrate that additional phosphopeptides are observed following both partial digestion and overdigestion. Finally, we show that Tyr-1086 can be phosphorylated in intact cells.

scholarly journals Alix/AIP1 Antagonizes Epidermal Growth Factor Receptor Downregulation by the Cbl-SETA/CIN85 Complex

2004 ◽  
Vol 24 (20) ◽  
pp. 8981-8993 ◽  
Author(s):  
Mirko H. H. Schmidt ◽  
Daniela Hoeller ◽  
Jiuhong Yu ◽  
Frank B. Furnari ◽  
Webster K. Cavenee ◽  
...  
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Growth Factor Receptor ◽  
Receptor Internalization ◽  
Interacting Protein ◽  
Low Intensity ◽  
C Terminus ◽  
Epidermal Growth ◽  
Interfering Rna

ABSTRACT The assembly of the Cbl-SETA/CIN85-endophilin complex at the C terminus of the epidermal growth factor receptor (EGFR) following ligand activation mediates its internalization and ubiquitination. We found that the SETA/CIN85-interacting protein Alix/AIP1, which also binds endophilins, modulates this complex. Alix was found to associate indirectly with EGFR, regardless of its activation state, and with ΔEGFR, which signals at low intensity and does not bind Cbls or SETA/CIN85. In agreement with this, Alix interaction did not occur via SETA/CIN85. However, SETA/CIN85 and Alix were capable of mutually promoting their interaction with the EGFR. Increasing the level of Alix weakened the interaction between SETA/CIN85 and Cbl and reduced the tyrosine phosphorylation of c-Cbl and the level of ubiquitination of EGFR, SETA/CIN85, and Cbls. This antagonism of the Cbl-SETA/CIN85 complex by Alix was reflected in its diminution of EGFR internalization. In agreement with this, small interfering RNA-mediated knockdown of Alix promoted EGFR internalization and downregulation. It has been suggested that SETA/CIN85 promotes receptor internalization by recruiting endophilins. However, Alix was also capable of increasing the level of endophilin associated with EGFR, implying that this is not sufficient to promote receptor internalization. We propose that Alix inhibits EGFR internalization by attenuating the interaction between Cbl and SETA/CIN85 and by inhibiting Cbl-mediated ubiquitination of the EGFR.

scholarly journals Conversion of a phosphoseryl/threonyl phosphatase into a phosphotyrosyl phosphatase

1988 ◽  
Vol 256 (3) ◽  
pp. 1029-1034 ◽  
Author(s):  
J Goris ◽  
C J Pallen ◽  
P J Parker ◽  
J Hermann ◽  
M D Waterfield ◽  
...  
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Phosphatase Activity ◽  
Growth Factor Receptor ◽  
Xenopus Laevis Oocytes ◽  
Rous Sarcoma ◽  
Sarcoma Virus ◽  
Epidermal Growth ◽  
Autophosphorylation Site

By use of the autophosphorylated epidermal-growth-factor receptor and the synthetic peptide RRLIE-DAEY(P)AARG, representing an autophosphorylation site of the transforming protein of Rous-sarcoma virus, it is demonstrated that the phosphotyrosyl phosphatase activity of the polycation-stimulated phosphatases is substantially increased by an enzyme-directed effect of ATP or PPi. Concomitant with this increase in phosphotyrosyl phosphatase activity, the phosphorylase phosphatase activity is decreased, thus dramatically changing the substrate specificity of these enzymes. The dephosphorylation of four different phosphotyrosyl sites of the epidermal-growth-factor receptor is neither consecutive nor at random, but a preferred dephosphorylation of the P1 site over the P3 greater than P2 greater than P4 sites is observed. This phosphatase activity represents a substantial fraction of the total phosphotyrosyl phosphatase activity in the post-mitochondrial supernatant of Xenopus laevis oocytes.

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