VITAMIN K, METABOLISM AND FUNCTION

描述：了解维生素K依赖蛋白质将需要 深入了解它们的生物合成和调节。 这些蛋白质的独特之处 维生素K依赖性翻译后修饰 的 修饰是通过羧化酶进行的，羧化酶是蛋白质的一个组成部分。 ER膜，其使用还原形式的维生素K（维生素KH 2）作为 辅因子 还原辅因子是由酶维生素K 3，4-环氧化物还原酶（VKOR）是抗凝药物的靶点 华法林 尽管有许多纯化VKOR的尝试， 还没有鉴定出构成该酶的组分。 的 申请人已经能够证明VKOR是ER中的酶复合物 他们提出复合物的组装类似于 脂氧合酶复合物在核膜上的组装。 两 酶包含谷胱甘肽-S-转移酶基因家族的一个成员 作为脂质蛋白酶复合物的一部分。 实验被提议为 完成VKOR酶复合物的模型，并揭示基础 对华法林有遗传抗性 重组VKOR将用于增加 细胞系产生功能性凝血因子VII的能力， 九. 我们假设VKOR产生的维生素KH 2辅因子是一种 这些重组蛋白的细胞生产的限制因素。 虽然8-10种不同的维生素K依赖蛋白已被证明是 只有一些是在肝外进行的。 它们包括 凝血因子凝血酶原和蛋白S，生长停滞特异性 基因6产物Gas 6和骨和软骨驻留蛋白， 骨钙素和基质GLA蛋白（MGP）。 在最后一个具体目标中， 应用实验提出了确定新的维生素K依赖 维生素K依赖性放射性标记的蛋白质。 拟议 实验将更好地了解维生素K代谢， 维生素K的功能和对预防医学的影响有关 重组维生素K依赖性凝血因子和华法林 抗凝 这些实验也应该有助于令人兴奋的， 肝外维生素K依赖性的研究领域迅速扩大 proteins.

DESCRIPTION: Understanding vitamin K-dependent proteins will require insight into their biosynthesis and regulation. Unique for these proteins is their vitamin K-dependent post-translational modification. The modification is carried out by the _-carboxylase, an integral protein of the ER membrane which uses the reduced form of vitamin K (vitamin KH2) as cofactor. The reduced cofactor is produced by the enzyme Vitamin K 3,4-Epoxide reductase (VKOR) which is the target for the anticoagulant drug warfarin. Despite numerous attempts to purify VKOR, the molecular components that constitute the enzyme have not been identified. The applicants have been able to show that VKOR is an enzyme complex in the ER membrane and they propose that assembly of the complex is similar to assembly of the lipoxygenase complex on the nuclear envelope membrane. Both enzymes incorporates a member of the glutathione-S-transferase gene family as part of the lipid-protein enzyme complex. Experiments are proposed to complete the model of the VKOR enzyme complex and unveil the basis for genetic resistance to warfarin. Recombinant VKOR will be used to increase the capacity of cell lines to produce functional clotting factors VII and IX. It is our hypothesis that vitamin KH2 cofactor production by VKOR is a limiting factor in cellular production of these recombinant proteins. Although 8-10 different vitamin K-dependent proteins have been shown to be made extrahepatically only some have been identified. They include the coagulation factors prothrombin and protein S, the growth arrest specific gene 6 product Gas6 and the bone and cartilage resident proteins, osteocalsin and matrix GLA protein (MGP). In the last specific aim of this application experiments are proposed to identify new vitamin K-dependent proteins by vitamin K-dependent radioactive labeling. The proposed experiments will provide a better understanding of vitamin K metabolism and vitamin K function and have an impact on prophylactic medicine concerned with recombinant vitamin K-dependent coagulation factors and warfarin anticoagulation. The experiments should also contribute to the exciting, rapidly expanding area of research on extra-hepatic vitamin K-dependent proteins.