Murata M, Onomichi K, Eto Y, Shibai H, Muramatsu M
Central Research Labortories, Ajinomoto Co., Inc., Kawasaki, Japan.
Biochem Biophys Res Commun. 1988 Feb 29;151(1):230-5. doi: 10.1016/0006-291x(88)90583-9.
Plasmid DNA containing EDF subunit cDNA and mouse dihydrofolate reductase (DHFR) cDNA was transfected into CHO DHFR- cells by the calcium-phosphate method. DHFR positive transformants secreted recombinant EDF (r-EDF) constitutively in an active form and accumulated it in the conditioned medium. Furthermore, cells which were resistant to methotrexate (MTX : 0.5 microM) secreted r-EDF up to 1 microgram/ml. r-EDF was identical to natural EDF (n-EDF) produced by human acute monocytic leukemia cell line, THP-1, as regards its dimeric structure and a biological activity.
通过磷酸钙法将含有EDF亚基cDNA和小鼠二氢叶酸还原酶（DHFR）cDNA的质粒DNA转染到CHO DHFR-细胞中。DHFR阳性转化体以活性形式持续分泌重组EDF（r-EDF），并将其积累在条件培养基中。此外，对甲氨蝶呤（MTX：0.5微摩尔）耐药的细胞分泌的r-EDF高达1微克/毫升。r-EDF在其二聚体结构和生物活性方面与人急性单核细胞白血病细胞系THP-1产生的天然EDF（n-EDF）相同。
