Structure and function of polyamine transport systems and NMDA receptors

1.研究了多胺在酿酒酵母中的转运。(1)位于质膜上的TPO1催化多胺的排泄。酪蛋白激酶1磷酸化Ser^<19>蛋白激酶C和Thr^<52>蛋白激酶，增强了TPO1的转运活性。通过cAMP依赖性蛋白激酶1和2在Ser^<342>位点磷酸化，TPO1从内质网向质膜的分选得到加强。(2) YKL174c编码的TPO5可催化腐胺和亚精胺的排泄，并定位于高尔基或后高尔基分泌囊泡，提示TPO5参与了多胺排泄的分泌和内噬途径。(3)我们发现位于质膜上的尿素转运蛋白DUR3和s -腺苷蛋氨酸转运蛋白SAM3优先催化多胺的摄取，并且这两种mrna的表达都被介质中多胺的存在所抑制。NMDA （n -甲基- d -天冬氨酸）受体是谷氨酸受体的一个亚型，参与中枢神经系统的可塑性。研究了各种蒽醌多胺（AQP）对非洲爪蟾卵母细胞中表达的NMDA受体的影响。所有AQP衍生物均抑制NR1/NR2受体在-70 mV电压下对卵母细胞的反应。该块与电压密切相关。AQ34可抑制NR1/NR2受体的反应，但对AMPA受体的反应无抑制作用，提示AQ34是优先的NMDA拮抗剂。使用突变体NR1和NR2亚基的实验结果确定了影响AQ34阻断的残基。这些残留物位于选择性过滤器/通道最窄处的外前庭和低于选择性过滤器水平的内前庭。纯化了NMDA受体亚基调控结构域（R-domain）蛋白，并测定了其性质。提示精胺和伊芬普罗地尔在r结构域蛋白上的结合位点不同。少

1.Polyamine transport in Saccharomyces cerevisiae was studied. (1)TPO1, located on the plasma membrane, catalyzed the excretion of polyamines. The transport activity of TPO1 was enhanced through phosphorylation at Ser^<19> protein kinase C and at Thr^<52> by casein kinase 1. Sorting of TPO1 from the endoplasmic reticulum to the plasma membrane was enhanced through phosphorylation at Ser^<342> by cAMP dependent protein kinases 1 and 2. (2)TPO5 encoded by YKL174c catalyzed the excretion of putrescine and spermidine, and it was localized on Golgi or post-Golgi secretory vesicles, suggesting that secretory and endocytic pathways, are involved in the excretion of polyamines by TPO5. (3)We found that urea transporter DUR3 and S-adenosylmethionine transporter SAM3, located on plasma membrane, catalyze polyamine uptake preferentially, and that the expression of both mRNAs were repressed by the presence of polyamines in medium.2.NMDA (N-methyl-D-aspartate) receptor is a subtype of glutamate rec … More eptors and involved in the plasticity of central nerves system. The effects of various anthraquinone polyamines (AQP) were studied at NMDA receptors expressed in Xenopus laevis oocytes. All AQP derivatives inhibited responses of NR1/NR2 receptors in oocytes voltage-clamped at -70 mV. The block was strongly voltage-dependent. AQ spermidine (AQ34) inhibited responses of NR1/NR2 receptors but did not inhibit responses of AMPA receptors indicating that AQ34 is preferential NMDA antagonists. Results of experiments using mutant NR1 and NR2 subunits identified residues that influence block by AQ34. These residues are located in the outer vestibule at the selectivity filter/narrowest constriction of the channel and in the inner vestibule below the level of the selectivity filter. Regulatory domain (R-domain) proteins of NMDA receptor subunits were purified and the properties of the proteins were determined. It was suggested that binding sites of spermine and ifenprodil on R-domain proteins are different each other. Less