A tyrosine-phosphorylated carboxy-terminal peptide of the fibroblast growth factor receptor (Flg) is a binding site for the SH2 domain of phospholipase C-gamma 1.
Phospholipase C-gamma (PLC-gamma) is a substrate of the fibroblast growth factor receptor (FGFR; encoded by the flg gene) and other receptors with tyrosine kinase activity. It has been demonstrated that the src homology region 2 (SH2 domain) of PLC-gamma and of other signalling molecules such as GTPase-activating protein and phosphatidylinositol 3-kinase-associated p85 direct their binding toward tyrosine-autophosphorylated regions of the epidermal growth factor or platelet-derived growth factor receptor. In this report, we describe the identification of Tyr-766 as an autophosphorylation site of flg-encoded FGFR by direct sequencing of a tyrosine-phosphorylated tryptic peptide isolated from the cytoplasmic domain of FGFR expressed in Escherichia coli. The same phosphopeptide was found in wild-type FGFR phosphorylated either in vitro or in living cells. Like other growth factor receptors, tyrosine-phosphorylated wild-type FGFR or its cytoplasmic domain becomes associated with intact PLC-gamma or with a fusion protein containing the SH2 domain of PLC-gamma. To delineate the site of association, we have examined the capacity of a 28-amino-acid tryptic peptide containing phosphorylated Tyr-766 to bind to various constructs containing SH2 and other domains of PLC-gamma. It is demonstrated that the tyrosine-phosphorylated peptide binds specifically to the SH2 domain but not to the SH3 domain or other regions of PLC-gamma. Hence, Tyr-766 and its flanking sequences represent a major binding site in FGFR for PLC-gamma. Alignment of the amino acid sequences surrounding Tyr-766 with corresponding regions of other FGFRs revealed conserved tyrosine residues in all known members of the FGFR family. We propose that homologous tyrosine-phosphorylated regions in other FGFRs also function as binding sites for PLC-gamma and therefore are involved in coupling to phosphatidylinositol breakdown.
Mohammadi
M
M
Department of Pharmacology, New York University Medical Center, New York 10016.
Honegger
A M
AM
Rotin
D
D
Fischer
R
R
Bellot
F
F
Li
W
W
Dionne
C A
CA
Jaye
M
M
Rubinstein
M
M
Schlessinger
J
J
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000378:metabolism; D000091344:Filaggrin Proteins; D006801:Humans; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011233:Precipitin Tests; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017468:Receptors, Fibroblast Growth Factor; D016415:Sequence Alignment; D013604:T-Phages / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism
C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D011956:Receptors, Cell Surface; D017468:Receptors, Fibroblast Growth Factor; D014443:Tyrosine; D010738:Type C Phospholipases