Differential basal protein tyrosine phosphorylation in natural killer (NK) and T cells: a biochemical correlate of lymphoid functional activity.
Despite the similarities between natural killer (NK) and T cells, these lymphocytes have dramatically different functional phenotypes. To identify potential biochemical parameters that correlate with the "primed" NK phenotype, we have investigated protein tyrosine phosphorylation in NK and T cells. Examination of tyrosyl phosphorylation in NK cells showed that they have higher levels of phosphorylation than resting T cells. Consistent with this, the concentrations of the tyrosine kinase inhibitor, herbimycin A, required to inhibit FcR-mediated Ca2+ flux in NK cells were much higher than those required for inhibition of T cell receptor-mediated Ca2+ mobilization. Differences in phosphorylation were not due to purification artifact lymphocyte src-family kinase, p56lck or the protein tyrosine phosphatase CD45. Thus, we have identified high basal tyrosyl phosphorylation as a striking biochemical feature of NK cells that correlates with the unique functions of this subset.
McVicar
D W
DW
Laboratory of Experimental Immunology, NCI-FCRDC, Frederick, Maryland 21702-1201, USA.
Blake
T B
TB
Burns
C M
CM
Conlon
K C
KC
Ortaldo
J R
JR
O'Shea
J J
JJ
D015496:CD4-Positive T-Lymphocytes / Q000201:enzymology; D018414:CD8-Positive T-Lymphocytes / Q000201:enzymology; D002469:Cell Separation; D006801:Humans; D007694:Killer Cells, Natural / Q000201:enzymology* / Q000276:immunology / Q000378:metabolism*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011946:Receptors, Antigen / Q000378:metabolism; D013379:Substrate Specificity; D013601:T-Lymphocytes / Q000201:enzymology* / Q000276:immunology / Q000378:metabolism*
D011946:Receptors, Antigen; D011505:Protein-Tyrosine Kinases