Grb10/GrbIR as an in vivo substrate of Tec tyrosine kinase.
BACKGROUND
Tec is a member of the recently emerging subfamily among nonreceptor protein-tyrosine kinases (PTKs). Although many members of this family have been shown to be involved in a wide range of cytokine-mediated signalling systems, the molecular mechanism by which they exert in vivo effects remains obscure. To gain insights into the downstream pathways of Tec, we here looked for Tec-interacting proteins (TIPs) by using the yeast two-hybrid screening.


RESULTS
One of TIPs turned out to be Grb10/GrbIR, which carries one pleckstrin homology domain and one Src homology 2 domain. Grb10/GrbIR was known to bind receptor PTKs in a ligand-dependent fashion, but not to be phosphorylated on tyrosine residues. In a transient expression system in human kidney 293 cells, however, Grb10/GrbIR becomes profoundly tyrosine-phosphorylated by Tec, but not by Syk, Jak2 or insulin receptor. We also reveal that expression of Grb10/GrbIR suppresses the cytokine-driven and Tec-driven activation of the c-fos promoter.


CONCLUSIONS
Our results indicate a novel role of Grb10/GrbIR as an effector molecule to a subset of nonreceptor PTKs.
Mano
H
H
Department of Molecular Biology, Jichi Medical School, Tochigi, Japan. hmano@jichi.ac.jp
Ohya
K
K
Miyazato
A
A
Yamashita
Y
Y
Ogawa
W
W
Inazawa
J
J
Ikeda
U
U
Shimada
K
K
Hatake
K
K
Kasuga
M
M
Ozawa
K
K
Kajigaya
S
S
D000595:Amino Acid Sequence; D002460:Cell Line; D002897:Chromosomes, Human, Pair 7 / Q000235:genetics; D003001:Cloning, Molecular; D018076:DNA, Complementary; D051383:GRB10 Adaptor Protein; D005786:Gene Expression Regulation / Q000235:genetics; D016762:Genes, fos / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D010766:Phosphorylation; D020161:Physical Chromosome Mapping; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011506:Proteins / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000502:physiology*; D013379:Substrate Specificity; D014443:Tyrosine / Q000378:metabolism
D018076:DNA, Complementary; D011506:Proteins; D012333:RNA, Messenger; D051383:GRB10 Adaptor Protein; D014443:Tyrosine; C089848:Tec protein-tyrosine kinase; D011505:Protein-Tyrosine Kinases