Mitchell A M, Manley S W, Mortimer R H
Conjoint Endocrine Laboratory, Royal Brisbane Hosptial, Queensland, Australia.
Mol Cell Endocrinol. 1992 Sep;87(1-3):139-45. doi: 10.1016/0303-7207(92)90242-x.
We studied uptake of L-triiodothyronine (T3) by the human choriocarcinoma cell line, JAR. Uptake was time dependent with a half-time of 56.2 +/- 7.2 min (mean +/- SEM, n = 4). A non-saturable component accounted for about 24% of total uptake. We found a single saturable uptake mechanism with a calculated Michaelis constant (Km) of 586 +/- 206 nM (n = 9) and a corresponding maximum velocity of 17.0 +/- 5.7 pmol/min per mg protein (n = 9), values similar to those we have described recently in cultured normal human trophoblast cells. Uptake was dependent on temperature and intracellular energy, being reduced at lower temperatures and in the presence of potassium cyanide. It was independent of the Na+ gradient across the cell membrane and the presence of Na+ in the external medium, but was affected by the cell membrane potential.
我们研究了人绒毛膜癌细胞系JAR对L-三碘甲状腺原氨酸（T3）的摄取。摄取呈时间依赖性，半衰期为56.2±7.2分钟（平均值±标准误，n = 4）。非饱和成分约占总摄取量的24%。我们发现了一种单一的饱和摄取机制，计算得出的米氏常数（Km）为586±206 nM（n = 9），相应的最大速度为每毫克蛋白质17.0±5.7 pmol/分钟（n = 9），这些值与我们最近在培养的正常人滋养层细胞中描述的值相似。摄取依赖于温度和细胞内能量，在较低温度下和存在氰化钾时摄取减少。它与跨细胞膜的Na+梯度以及细胞外培养基中Na+的存在无关，但受细胞膜电位的影响。
