Cloning and characterization of Lnk, a signal transduction protein that links T-cell receptor activation signal to phospholipase C gamma 1, Grb2, and phosphatidylinositol 3-kinase.
A cDNA encoding a signal transduction protein with a Src homology 2 (SH2) domain and a tyrosine phosphorylation site was cloned from a rat lymph node cDNA library. This protein, which we designate Lnk, has a calculated molecular weight of 33,988. When T lymphocytes were activated by antibody-mediated crosslinking of the T-cell receptor and CD4, Lnk became tyrosine phosphorylated. In activated T lymphocytes, phospholipase C gamma 1, phosphatidylinositol 3-kinase, and Grb-2 coimmunoprecipitated with Lnk. Our results suggest that Lnk becomes tyrosine phosphorylated and links the immediate tyrosine phosphorylation signals of the TCR to the distal phosphatidylinositol 3-kinase, phospholipase C gamma 1 and Ras signaling pathways through its multifunctional tyrosine phosphorylation site.
W. Alton Jones Cell Science Center, Inc., Lake Placid, NY 12946, USA.
X
X
Huang
Y
Y
Li
K
K
Tanaka
K G
KG
Moore
J I
JI
Hayashi
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D018076:DNA, Complementary; D051380:GRB2 Adaptor Protein; D007527:Isoenzymes / Q000378:metabolism*; D008198:Lymph Nodes / Q000166:cytology; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D008970:Molecular Weight; D019869:Phosphatidylinositol 3-Kinases; D051966:Phospholipase C gamma; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000235:genetics* / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism*; D018909:src Homology Domains
D048868:Adaptor Proteins, Signal Transducing; D018076:DNA, Complementary; D051380:GRB2 Adaptor Protein; D007527:Isoenzymes; D019869:Phosphatidylinositol 3-Kinases; D051966:Phospholipase C gamma; D017853:Phosphotransferases (Alcohol Group Acceptor); D011506:Proteins; D011948:Receptors, Antigen, T-Cell; D010738:Type C Phospholipases; C097176:Sh2b3 protein, rat