Catalytic specificity of protein-tyrosine kinases is critical for selective signalling.
How do distinct protein-tyrosine kinases activate specific down-stream events? Src-homology-2 (SH2) domains on tyrosine kinases or targets of tyrosine kinases recognize phosphotyrosine in a specific sequence context and thereby provide some specificity. The role of the catalytic site of tyrosine kinases in determining target specificity has not been fully investigated. Here we use a degenerate peptide library to show that each of nine tyrosine kinases investigated has a unique optimal peptide substrate. We find that the cytosolic tyrosine kinases preferentially phosphorylate peptides recognized by their own SH2 domains or closely related SH2 domains (group I; ref. 3), whereas receptor tyrosine kinases preferentially phosphorylate peptides recognized by subsets of group III SH2 domains. The importance of these findings for human disease is underscored by our observation that a point mutation in the RET receptor-type tyrosine kinase, which causes multiple endocrine neoplasia type 2B, results in a shift in peptide substrate specificity.
Department of Medicine, Beth Israel Hospital, Boston, Massachusetts 02215.
Z
Z
Songyang
K L
KL
Carraway
M J
MJ
Eck
S C
SC
Harrison
R A
RA
Feldman
M
M
Mohammadi
J
J
Schlessinger
S R
SR
Hubbard
D P
DP
Smith
C
C
Eng
D000595:Amino Acid Sequence; D000818:Animals; D002384:Catalysis; D002460:Cell Line; D003593:Cytoplasm / Q000201:enzymology; D029721:Drosophila Proteins; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013379:Substrate Specificity
D029721:Drosophila Proteins; D010455:Peptides; D011518:Proto-Oncogene Proteins; D011505:Protein-Tyrosine Kinases; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases; C416649:Ret protein, Drosophila