Differentiation of peptide molecular recognition by phospholipase C gamma-1 Src homology-2 domain and a mutant Tyr phosphatase PTP1bC215S.
Activated epidermal growth factor receptor (EGFR) undergoes autophosphorylation on several cytoplasmic tyrosine residues, which may then associate with the src homology-2 (SH2) domains of effector proteins such as phospholipase C gamma-1 (PLC gamma-1). Specific phosphotyrosine (pTyr)-modified EGFR fragment peptides can inhibit this intermolecular binding between activated EGFR and a tandem amino- and carboxy-terminal (N/C) SH2 protein construct derived from PLC gamma-1. In this study, we further explored the molecular recognition of phosphorylated EGFR988-998 (Asp-Ala-Asp-Glu-pTyr-Leu-Ile-Pro-Gln-Gln-Gly, I) by PLC gamma-1 N/C SH2 in terms of singular Ala substitutions for amino acid residues N- and C-terminal to the pTyr (P site) of phosphopeptide I. Comparison of the extent to which these phosphopeptides inhibited binding of PLC gamma-1 N/C SH2 to activated EGFR showed the critical importance of amino acid side chains at positions P+2 (Ile994), P+3 (Pro995), and P+4 (Gln996). Relative to phosphopeptide I, multiple Ala substitution throughout the N-terminal sequence, N-terminal sequence, N-terminal truncation, or dephosphorylation of pTyr each resulted in significantly decreased binding to PLC gamma-1 N/C SH2. These structure-activity results were analyzed by molecular modeling studies of the predicted binding of phosphopeptide I to each the N- and C-terminal SH2 domains of PLC gamma-1.(ABSTRACT TRUNCATED AT 250 WORDS)
MacLean
D
D
Department of Chemistry, Parke-Davis Pharmaceutical Research, Ann Arbor, Michigan 48105, USA.
Sefler
A M
AM
Zhu
G
G
Decker
S J
SJ
Saltiel
A R
AR
Singh
J
J
McNamara
D
D
Dobrusin
E M
EM
Sawyer
T K
TK
D000595:Amino Acid Sequence; D001665:Binding Sites; D003196:Computer Graphics; D066246:ErbB Receptors / Q000737:chemistry / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D008969:Molecular Sequence Data; D051966:Phospholipase C gamma; D010748:Phosphopeptides / Q000378:metabolism; D010766:Phosphorylation; D017354:Point Mutation / Q000235:genetics; D017434:Protein Structure, Tertiary; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics; D016415:Sequence Alignment; D010738:Type C Phospholipases / Q000378:metabolism*
D007527:Isoenzymes; D010748:Phosphopeptides; D011993:Recombinant Fusion Proteins; D066246:ErbB Receptors; D017027:Protein Tyrosine Phosphatases; D010738:Type C Phospholipases; D051966:Phospholipase C gamma