MECHANISMS OF BILE PIGMENT EXCRETION

采用分子、细胞生物学、生物化学和免疫形态学方法， 我们要求继续长期研究参与 各种有机分子的转移（即，胆汁酸，色素，药物， 代谢物和其他）从血液到胆汁并返回。 特别是，我们寻求确定结构，功能和监管 四种胆小管转运蛋白的功能障碍， 在发育性、获得性和遗传性胆汁淤积中： (a)ATP依赖转运蛋白的克隆、测序和纯化 胆汁酸和非胆汁酸有机阴离子在突变体出芽和 fisson酵母，以产生用于鉴定和研究的探针 哺乳动物同源物的结构和调节（由于低 丰富，使纯化和克隆的努力受挫）。 (b)初步证据表明，主要的多药耐药基因mdr 2 抗性基因产物存在于小管中，具有ATP依赖性磷脂 移位酶活性和增加磷脂从细胞血浆中释放 膜。 因此，我们试图确定这些过程是如何 与小管磷脂转运有关， mdr 2在“胆管消失综合征”中的作用 (c)小管Na ~+的克隆、测序及调控研究 在肝细胞中保存核苷的依赖性嘌呤转运蛋白。

Using molecular, cell biologic, biochemical and immunomorphologic methods, we request to continue long range studies of mechanisms involved in the transfer of various organic molecules (i.e., bile acids, pigments, drugs, metabolites and others) from blood to bile and back. In particular, we seek to determine the structure, function and regulation of four bile canalicular transporters and, ultimately, their dysfunction in developmental, acquired and inheritable cholestasis: (a) Cloning, sequencing and purification of the ATP-dependent transporters for bile acids and nonbile acid organic anions in mutant budding and fisson yeast in order to generate probes for identifying and studying structure and regulation of the mammalian homologues (which, due to low abundance, have frustrated efforts at purification and cloning). (b) Preliminary evidence suggests that mdr2, the major multidrug resistance gene product in the canaliculus, has ATP-dependent phospholipid translocase activity and increases phospholipid release from cell plasma membranes. Therefore, we seek to determine how these processes are related with respect to canalicular phospholipid transport, and the possible role of mdr2 in the "vanishing bile duct syndrome". (c) Cloning, sequencing and study of the regulation of the canalicular Na+ dependent purine transporter which conserves nucleosides in hepatocytes.