REGULATION OF THE CYTOPLASMIC ACCUMULATION OF 5-METHYLTETRAHYDROFOLATE IN MA104 CELLS IS INDEPENDENT OF FOLATE RECEPTOR REGULATION
REGULATION OF THE CYTOPLASMIC ACCUMULATION OF 5-METHYLTETRAHYDROFOLATE IN MA104 CELLS IS INDEPENDENT OF FOLATE RECEPTOR REGULATION
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DOI：
10.1172/jci114310
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发表时间：
1989-11-01
影响因子：
15.9
通讯作者：
ANDERSON, RGW
中科院分区：
文献类型：
--
作者：
KAMEN, BA;JOHNSON, CA;ANDERSON, RGW
为了更好地理解叶酸受体（也称为膜叶酸结合剂）如何能够将5-甲基四氢叶酸递送到叶酸耗尽的MA 104细胞的细胞质中，我们检查了从细胞表面移动到细胞质中的动力学。将结合的5-甲基四氢叶酸以0.9-1.0 pmol/106细胞/h的速率转移到耐酸膜隔室中。这种叶酸以相同的速率出现在细胞质中。此外，细胞质5-甲基四氢叶酸以0.6-0.7 pmol/106细胞/h的速率变成多谷氨酸。然而，一旦细胞内5-甲基四氢叶酸达到5-7 pmol/106个细胞，即使叶酸受体仍然具有功能，细胞质积累也会受到显著抑制。因此，5-甲基四氢叶酸积累的急性调节似乎是通过控制维生素从受体进入细胞质的运动来实现的。
To better understand how the folate receptor (also known as the membrane folate binder) is able to deliver 5-methyltetrahydrofolic acid to the cytoplasm of folate-depleted MA104 cells, we have examined the kinetics of movement from the cell surface into the cytoplasm. Bound 5-methyltetrahydrofolic acid was transferred into an acid-resistant membrane compartment at the rate of 0.9-1.0 pmol/106 cells per h. This folate appeared in the cytoplasm at the same rate. Furthermore, cytoplasmic 5-methyltetrahydrofolic acid became polyglutamated at the rate of 0.6-0.7 pmol/106 cells per h. As soon as intracellular 5-methyltetrahydrofolate reached 5-7 pmol/106 cells, however, cytoplasmic accumulation was markedly inhibited even though the folate receptor remained functional. Therefore, the acute regulation of 5-methyltetrahydrofolic acid accumulation appears to be achieved by controlling the movement of the vitamin from the receptor into the cytoplasm of the cell.