The phosphorylated 1169-tyrosine containing region of flt-1 kinase (VEGFR-1) is a major binding site for PLCgamma.
Flt-1, a tyrosine kinase receptor for vascular endothelial growth factor (VEGF), plays important roles in the angiogenesis required for embryogenesis and in monocyte/macrophage migration. However, the signal transduction of Flt-1 is poorly understood due to its very weak tyrosine kinase activity. Therefore, we overexpressed Flt-1 in insect cells using the Baculovirus system in order to examine for autophosphorylation sites and association with adapter molecules such as phospholipase Cgamma-1 (PLCgamma). Tyr-1169 and Tyr-1213 on Flt-1 were found to be auto-phosphorylated, but only a phenylalanine mutant of Tyr-1169 strongly suppressed its association with PLCgamma. In Flt-1 overexpressing NIH3T3 cells, VEGF induced autophosphorylation of Flt-1, tyrosine-phosphorylation of PLCgamma and protein kinase C-dependent activation of MAP kinase. These results strongly suggest that Tyr-1169 on Flt-1 is a major binding site for PLCgamma and important for Flt-1 signal transduction within the cell.
Sawano
A
A
Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, 108, Japan.
Takahashi
T
T
Yamaguchi
S
S
Shibuya
M
M
D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D051379:Mice; D051966:Phospholipase C gamma; D010766:Phosphorylation; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000737:chemistry / Q000378:metabolism*; D011975:Receptors, Mitogen / Q000737:chemistry / Q000378:metabolism; D040262:Receptors, Vascular Endothelial Growth Factor; D010738:Type C Phospholipases / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*
D007527:Isoenzymes; D017978:Receptors, Growth Factor; D011975:Receptors, Mitogen; D014443:Tyrosine; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor; D010738:Type C Phospholipases; D051966:Phospholipase C gamma