Grollman E F, Saji M, Shimura Y, Lau J T, Ashwell G
Laboratory of Biochemistry and Metabolism, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
J Biol Chem. 1993 Feb 15;268(5):3604-9.
The present study, utilizing the hormone-responsive rat thyroid cell line FRTL-5, presents evidence establishing the regulatory role of thyrotropin in modulating mRNA for beta-galactoside alpha 2,6-sialytransferase, the enzyme responsible for the expression of alpha 2,6-linked sialic acid. Both the cell surface membrane and the thyroglobulin secreted by cells grown in the presence of this hormone exhibit a marked decrease in the level of alpha 2,6-bound sialic acid with little or no change in the number of alpha 2,3-sialic acid residues. An additional, and unexpected, sequel is the finding of a coordinated decrease in all of the core monosaccharide constituents of the secreted thyroglobulin. Both of the above phenomenological changes appear to be at some variance with previously described systems wherein thyrotropin was deemed to increase glycosylation. It is anticipated that further resolution of this apparent difference may provide a clearer definition for the role of the carbohydrate moiety in affecting the biological function of thyroglobulin.
本研究利用激素反应性大鼠甲状腺细胞系FRTL-5，提供了证据证实促甲状腺激素在调节β-半乳糖苷α2,6-唾液酸转移酶（负责α2,6-连接唾液酸表达的酶）的mRNA方面的调节作用。在这种激素存在下生长的细胞的细胞表面膜和分泌的甲状腺球蛋白，α2,6-结合唾液酸水平均显著降低，而α2,3-唾液酸残基数量几乎没有变化或没有变化。另一个意外的后续发现是，分泌的甲状腺球蛋白的所有核心单糖成分都出现了协同减少。上述两种现象学变化似乎与先前描述的促甲状腺激素被认为会增加糖基化的系统有所不同。预计进一步解决这一明显差异可能会更清楚地界定碳水化合物部分在影响甲状腺球蛋白生物学功能中的作用。
