Type 2 phosphatidylinositol 4-kinase is recruited to CD4 in response to CD4 cross-linking.
CD4 serves as a cell-cell adhesion molecule, with specific affinity for class II MHC molecules, and as a receptor for the human immunodeficiency virus type 1 (HIV-1) viral coat protein. Phosphoinositide (PI)-3-kinase and 1-phosphatidylinositol (PtdIns)-4-kinase activities were previously found to associate with the CD4:p56lck complex, but the protein responsible for PtdIns 4-kinase activity was not identified. Here we demonstrate that the 53 kDa type 2 PtdIns 4-kinase associates with CD4 using a monoclonal antibody specific for this enzyme. We also show that an increase in PtdIns 4-kinase activity is due to recruitment of the type 2 PtdIns 4-kinase protein to the CD4:p56lck complex after cross-linking with anti-CD4.
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Department of Medicine, Beth Israel Hospital, Boston, MA, USA.
Cantley
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D019870:1-Phosphatidylinositol 4-Kinase; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015704:CD4 Antigens / Q000378:metabolism*; D002448:Cell Adhesion; D002460:Cell Line; D003432:Cross-Linking Reagents; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D003432:Cross-Linking Reagents; C079851:OKT4A monoclonal antibody; D017853:Phosphotransferases (Alcohol Group Acceptor); D019870:1-Phosphatidylinositol 4-Kinase; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck)