Interactions of polyomavirus middle T with the SH2 domains of the pp85 subunit of phosphatidylinositol-3-kinase.
The binding of phosphatidylinositol-3-kinase to the polyomavirus middle T antigen is facilitated by tyrosine phosphorylation of middle T on residue 315. The pp85 subunit of phosphatidylinositol-3-kinase contains two SH2 domains, one in the middle of the molecule and one at the C terminus. When assayed by blotting with phosphorylated middle T, the more N-terminal SH2 domain is responsible for binding to middle T. When assayed in solution with glutathione S transferase fusions, both SH2s are capable of binding phosphorylated middle T. While both SH2 fusions can compete with intact pp85 for binding to middle T, the C-terminal SH2 is the more efficient of the two. Interaction between pp85 or its SH2 domains and middle T can be blocked by a synthetic peptide comprising the tyrosine phosphorylation sequence around middle T residue 315. Despite the fact that middle T can interact with both SH2s, these domains are not equivalent. Only the C-terminal SH2-middle T interaction was blocked by anti-SH2 antibody; the two SH2 fusions also interact with different cellular proteins.
Yoakim
M
M
Department of Biochemistry, Tufts University School of Medicine, Boston, Massachusetts 02111.
Hou
W
W
Liu
Y
Y
Carpenter
C L
CL
Kapeller
R
R
Schaffhausen
B S
BS
D019870:1-Phosphatidylinositol 4-Kinase; D016475:3T3 Cells; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism*; D001665:Binding Sites; D002472:Cell Transformation, Viral; D003001:Cloning, Molecular; D016391:Genes, src / Q000235:genetics; D051379:Mice; D008954:Models, Biological; D010750:Phosphoproteins / Q000378:metabolism; D010770:Phosphotransferases / Q000378:metabolism*; D019000:Phosphotyrosine; D011120:Polyomavirus / Q000378:metabolism*; D011487:Protein Conformation; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D000952:Antigens, Polyomavirus Transforming; D010750:Phosphoproteins; D019000:Phosphotyrosine; D014443:Tyrosine; D010770:Phosphotransferases; D019870:1-Phosphatidylinositol 4-Kinase