Phosphorylation of human interleukin-2 (IL-2).
Human interleukin-2 (IL-2) is a lymphokine which is capable of activating lymphocytes and supporting the long-term in vitro growth of activated T cell clones. Recombinant human IL-2, expressed in either E. coli or cos cells, was shown to be phosphorylated by protein kinase C. Phosphorylated IL-2 synthesized in E. coli was analyzed by SDS-PAGE, reverse phase HPLC, and tryptic peptide mapping. The phosphorylated tryptic peptide was identified as the N-terminal fragment containing a single phosphorylation site at the serine residue at position 7. There was no difference in biological activity between non-phosphorylated and phosphorylated IL-2, as determined by a T cell growth assay. Although the physiological role of phosphorylation of IL-2 is unclear, IL-2 can be labeled with [gamma-32P] ATP and protein kinase C to a high specific radioactivity, and the synthesis of biologically active 32p-labeled IL-2 may be useful for receptor-binding studies of the cells containing low level of phosphoprotein phosphotases.
Kung
H F
HF
LBP, BRMP, DCT, NCI-FCRF, Frederick, MD 21701.
Calvert
I
I
Bekesi
E
E
Khan
F R
FR
Huang
K P
KP
Oroszlan
S
S
Henderson
L E
LE
Copeland
T D
TD
Sowder
R C
RC
Wei
S J
SJ
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism
D000596:Amino Acids; D007376:Interleukin-2; D011994:Recombinant Proteins; D011493:Protein Kinase C