TY - JOUR
T1 - Human leukemia and normal leukocytes contain a species of immunoreactive but nonfunctional dihydrofolate reductase
AU - Rothenberg, S. P.
AU - Iqbal, M. P.
PY - 1982
Y1 - 1982
N2 - A quantitative radioimmunoassay has been developed for human dihydrofolate reductase (tetrahydrofolate dehydrogenase; 5,6,7,8-tetrahydrofolate:NADPH+ oxidoreductase, EC 1.5.1.3) by using antiserum raised in rabbits against the active enzyme purified from calf liver. An immunoreactive protein could be identified in the cytoplasm of chronic myelogenous leukemia cells, which contained no functional dihydrofolate reductase activity. Its concentration was stoichiometric to the volume of cytoplasm assayed and paralleled the standard curve obtained with purified enzyme, indicating that this protein in the human cells is antigenically similar to the homologous antigen. The concentration of this immunoreactive protein in the cytoplasm of human leukemia and normal leukocytes in all instances greatly exceeded the concentration of functional dihydrofolate reductase, which was measured by the binding of [3H]methotrexate. This nonfunctional immunoreactive protein in the cytoplasm and cytosol from two different samples of chronic myelogenous leukemia cells analyzed by gel filtration had an apparent molecular weight of 41,000, which is twice the molecular weight of the functional enzyme.
AB - A quantitative radioimmunoassay has been developed for human dihydrofolate reductase (tetrahydrofolate dehydrogenase; 5,6,7,8-tetrahydrofolate:NADPH+ oxidoreductase, EC 1.5.1.3) by using antiserum raised in rabbits against the active enzyme purified from calf liver. An immunoreactive protein could be identified in the cytoplasm of chronic myelogenous leukemia cells, which contained no functional dihydrofolate reductase activity. Its concentration was stoichiometric to the volume of cytoplasm assayed and paralleled the standard curve obtained with purified enzyme, indicating that this protein in the human cells is antigenically similar to the homologous antigen. The concentration of this immunoreactive protein in the cytoplasm of human leukemia and normal leukocytes in all instances greatly exceeded the concentration of functional dihydrofolate reductase, which was measured by the binding of [3H]methotrexate. This nonfunctional immunoreactive protein in the cytoplasm and cytosol from two different samples of chronic myelogenous leukemia cells analyzed by gel filtration had an apparent molecular weight of 41,000, which is twice the molecular weight of the functional enzyme.
UR - http://www.scopus.com/inward/record.url?scp=0020058121&partnerID=8YFLogxK
U2 - 10.1073/pnas.79.2.645
DO - 10.1073/pnas.79.2.645
M3 - Article
C2 - 6952216
AN - SCOPUS:0020058121
SN - 0027-8424
VL - 79
SP - 645
EP - 649
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 2 I
ER -