MOLELCULAR BIOLOGY OF PHOTOPIGMENTS

我们研究了它的结构、功能、发育进化、表位 视网膜S抗原的葡萄膜形成部位(48k蛋白)。基因的cDNA 从牛视网膜文库及其DNA中分离出S抗原 序列已经确定。预测的氨基酸序列为 与埃德曼降解法测定的S抗原完全匹配 方法。S抗原多肽与人的某些序列同源性 转导蛋白包括霍乱毒素、百日咳毒素和 肠毒素ADP核糖结合位点和嘌呤核苷酸结合位点。 S抗原是一种糖蛋白，其糖基是葡萄糖和 甘露糖。二级结构预测和圆二色谱分析 表明S抗原有一个以扩展为主的(β-折叠) 具有一个小的C-末端螺旋区的结构。两个人的位置 单抗结合部位和葡萄膜形成部位之一 S抗原已确定。这三个线性免疫原点是 定位于三个分离位点的20个氨基酸残基内。信使核糖核酸 S抗原的长度约为2kb，存在于杆状细胞中，但 在大多数锥体细胞中不存在。发现大部分的mRNAs 非常靠近细胞核，但在肌样细胞的大部分和 杆状内节的椭圆形。此外，S抗原mR NA也存在于 某些类型的松果体细胞。S抗原在小鼠体内只有一个基因， 人，说明视网膜和松果体的S抗原是相同的。这个 人和小鼠S抗原基因的部分分离和鉴定 人S抗原基因位于第3号染色体上。 14.

We have examined the structure, function, development evolution, epitopes and uveitogenic site of the retinal S-antigen (48k protein). The cDNAs of S-antigen have been isolated from bovine retina libraries and their DNA sequences have been determined. The predicted amino acid sequence was matched completely with that of S-antigen determined by Edman degradation method. S-antigen polypeptide has some sequence homologies with GAlpha-transducin including the cholera toxin, pertussis toxin and enterotoxin ADP-ribosylaation sites and purine nucleotide-binding sites. S-antigen is found to be a glycoprotein and its sugar moeity is glucose and mannose. Secondary structure prediction and circular dichroism analysis indicated that S-antigen has a predominantly extended (beta-sheet) structure with a small C-terminal helical region. The location of the two monoclonal antibodies binding sites and the one uveitogenic site of S-antigen has been determined. These three linear immunogenic sites were localized within 20 amino acid residues at three separated sites. The mRNA of S-antigen is approximately 2 kb long and present in the rod cells but not present in the majority of cone cells. The majority of mRNA was found very close to the nucleus but not found in the most part of myoid and ellipoid of the rod inner segments. Also S-antigen mRNA was present in certain types of pinealocytes. S-antigen has only one gene in mouse and human, indicating that the S-antigen of retina and pineal is the same. The S-antigen genes of human and mouse were isolated and identified by partial DNA sequences and the human S-antigen gene is located on the chromosome No. 14.