The extracellular domain of CD4 receptor possesses a protein kinase activity.
The CD4 receptor of T-helper cells is an essential participant in immune response formation and HIV infection. We report here that the extracellular domains of CD4 receptor can catalyze the phosphotransferase (kinase) reaction. Incubation of rsCD4 in solution with [gamma-32P]ATP results in the Ca2+-dependent autophosphorylation of the protein presumably at a His residue because the reaction is prevented by the diethylpyrocarbonate treatment. The rsCD4 phosphorylates milk casein or human plasma proteins as a Ser/Thr protein kinase.
Yakubov
L A
LA
Novosibirsk Institute of Bioorganic Chemistry, Siberian Division of Russian Academy of Sciences. yakubov@niboch.nsc.ru
Kit
Y Y
YY
Richter
V A
VA
Andreeva
A Y
AY
Karamyshev
V N
VN
Stein
C A
CA
Vlassov
V V
VV
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D015704:CD4 Antigens / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation; D011494:Protein Kinases / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D015704:CD4 Antigens; D011994:Recombinant Proteins; D000255:Adenosine Triphosphate; D011494:Protein Kinases