ANALYSIS OF TYROSINE SULFATION

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 这项合作是对酪氨酸硫酸盐化的广泛研究， 广泛存在的蛋白质和多肽激素的翻译后修饰 它们通过动物细胞的高尔基体系统。当项目开始的时候 仅限于一些参与消化的多肽激素 过程和一些，例如，CCK，都活跃在 胃肠道和中枢神经系统。这两种组织 表达不同但密切相关的受体。酪氨酸硫酸盐化 据估计，翻译后修饰大约发生在1% 大鼠蛋白质中的酪氨酸残留量。我们最初的论文集中在寻找 以及可以用来准确预测酪氨酸硫化的测试规则 站点(1，2，3)。这些初步研究得出的结论是 酪氨酸蛋白磺基转移酶，催化硫酸盐化 蛋白质和多肽中的酪氨酸残留量，底物相对较低 并可能修饰任何足够的酪氨酸残基 暴露在带负电荷的侧链附近。 最近发现，特定细胞因子的酪氨酸硫化作用 受体分子是某些感染模式的基本要求 并提高了其他感染方式的效率(5)。 此外，酪氨酸硫化已被证明是活性所必需的。 糖蛋白激素受体家族中的一些亚家族，似乎 在其他亚科中扮演类似的角色(6)。因此，我们一直在探索 其他受体家族可能需要酪氨酸硫化来 有效的或充分的活动。我们一直在关联我们的预测 酪氨酸硫酸盐化结合位点及其他生化信息 蛋白质链中受体结合部位的位置。 我们预测，32个跨膜肽受体中的49个酪氨酸是 硫酸盐化了。虽然我们没有结合已确认的 硫酸盐化地点，如跨物种的聚集和保护进入我们的 简介(职位特定评分矩阵，PSSM)，我们的预测网站 然而，它表现出了这些特征。观察到的守恒 表明有强大的进化压力来保存选定的 七种跨膜肽受体的生物活性。被预测的 酪氨酸硫化位点主要发生在胞外尾部和 细胞外环2，与其与结合相关联的区域 受体的口袋(4)。 酪氨酸硫化对蛋白质的翻译后修饰增强了 细胞外配体-受体相互作用的亲和力在免疫中的重要作用

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This collaboration has been a broadly based examination of tyrosine sulfation, a widespread posttranslational modification of proteins and peptide hormones that pass through the Golgi system of animal cells. When the project began it was limited to a number of the peptide hormones involved in the digestive process and some, for example Cholecystokinin (CCK), active both in the gastrointestinal tract and in the central nervous system. The two tissues express different but closely related receptors. The tyrosine sulfation posttranslational modification has been estimated to occur to about one percent of tyrosine residues in Rat proteins. Our initial papers focused on finding and testing rules that could be used to accurately predict tyrosine sulfation sites (1,2,3). These initial studies led to the conclusions that tyrosylprotein sulfotransferase, the enzyme that catalyzes the sulfation of tyrosine residues in proteins and peptides, has a relatively low substrate specificity and is likely to modify any tyrosine residue that is sufficiently exposed and is near negatively charged side chains. Recently it has been discovered that tyrosine sulfation of specific cytokine receptors molecules is an essential requirement for some modes of infection of the HIV-1 virus and increases the efficiency of other modes of infection (5). Additionally, tyrosine sulfation has been shown to be required for the activity of some subfamilies within the glycoprotein hormone receptors family and seems to play a similar role in other subfamilies (6). Thus we have been exploring the possibility that other receptor families may require tyrosine sulfation for either effective or full activity. We have been correlating our predictions of tyrosine sulfation binding sites with additional biochemical information about the location of receptor binding site within the protein chain. We predict that 49 tyrosines of 32 seven-transmembrane peptide receptors are sulfated. Although we did not incorporate characteristics of confirmed sulfation sites such as clustering and conservation across species into our profile (Position Specific Scoring Matrix, PSSM), our predicted sites nevertheless exhibited these characteristics. The observed conservation suggests that there are strong evolutionary pressures to preserve selected biological activity of seven-transmembrane peptide receptors. The predicted tyrosine sulfation sites predominantly occur in the extracellular tail and extracellular loop 2, regions consistent with their association with binding pockets of the receptor (4). Post-translational modification of proteins by tyrosine sulfation enhances the affinity of extracellular ligand-receptor interactions important in the immune