CHARACTERIZATION OF EXTRACELLULAR DOMAIN OF CA++ SENSING RECEPTOR

我们目前正在研究一种G蛋白偶联受体 通过细胞外钙(在毫摩尔范围内)与标准 七个跨膜区结构，但具有独特的，大约 600个氨基酸的胞外氨基末端结构域(ECD)。后者 含有多种天冬氨酸和谷氨酸残基，推测与 钙结合，9个假定的糖基化位点，多个半胱氨酸 在代谢性谷氨酸受体的相关ECD中保守 家族，以及一个推定的信号肽。质谱学正在被 用来表征完整的蛋白质和被消化的片段 帮助确定糖基化的数量、位置和性质的努力 以及可能的二硫化物。

We are currently working on a G protein-coupled receptor activated by extracellular Ca++ (in the millimolar range) with the standard seven transmembrane domain structure but with a unique, approximately 600 amino acid extracellular amino terminal domain (ECD). The latter contains multiple asp and glu residues speculated to be involved in Ca++ binding, 9 putative glycosylation sites, multiple cysteines conserved in the related ECD of the metabotropic glutamate receptor family, and a putative signal peptide. Mass spectrometry is being used to characterize both the intact protein and digested fragments in an effort to help define number, location and nature of glycosylation as well as possible disulfides.