SYNTHESIS OF THYROXINE TRANSPORT PROTEINS

甲状腺素转运蛋白的合成

• 批准号: 4689989
• 负责人: J ROBBINS
• 金额: --
• 依托单位: NAT INST OF ARTHRITIS, DIABETES, DIGESTIVE & KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/4689989
• 关键词: blood proteins; density gradient ultracentrifugation; globulins; human tissue; liver cells; messenger RNA; peptides; thyroxine analog; tissue /cell culture

Human hepatoma cell (HepG2) monolayer cultures has previously been shown to synthesize and secrete thyroxine-binding globulin (TBG). The present studies employed these cells to demonstrate that 27 K protein, a novel thyroxine-binding protein described in Project Z01 AM 45000-18, is also produced by the liver. Convincing evidence that TBG and 27 K protein are distinct proteins was obtained by showing that TBG mRNA and 27 K mRNA can be separated by sucrose gradient centrifugation. In vitro translation of 27 K mRNA and whole cell studies with (H3)mannose as precursor, or (S35)methionine in the presence of the glycosylation inhibitor, tunicamycin, proved that 27 K protein is nonglycosylated and does not appear to contain a pro-peptide. The kinetics of 27 K protein secretion was similar to that of albumin and faster than that of TBG, reflecting its non-glycoprotein nature. Earlier studies with monkey hepatoma cell cultures showed that 27 K protein was a much more prominent biosynthetic product than TBG in these cells.

人肝癌细胞 (HepG2) 单层培养物先前已被证明可以 合成和分泌甲状腺素结合球蛋白（TBG）。 现在的 研究利用这些细胞来证明 27 K 蛋白，一种新型的 Project Z01 AM 45000-18 中描述的甲状腺素结合蛋白，也是 由肝脏产生。 令人信服的证据表明 TBG 和 27 K 蛋白是 通过显示 TBG mRNA 和 27 K mRNA 可以获得不同的蛋白质 通过蔗糖梯度离心分离。 体外翻译 以 (H3) 甘露糖作为前体进行 27 K mRNA 和全细胞研究，或 (S35)甲硫氨酸在糖基化抑制剂存在下， 衣霉素，证明 27 K 蛋白是非糖基化的，并且不 似乎含有前肽。 27 K 蛋白分泌动力学 与白蛋白相似且比 TBG 更快，反映了其 非糖蛋白性质。 猴肝癌细胞的早期研究 培养物表明 27 K 蛋白是一种更为重要的生物合成蛋白 这些细胞中的产物比 TBG 更重要。