MOLELCULAR BIOLOGY OF PHOTOPIGMENTS

我们研究了其结构、功能、发育进化、表位 和视网膜S-抗原（48 k蛋白）的致葡萄膜位点。 的cdna 从牛视网膜文库中分离出S抗原， 序列已经确定。 预测的氨基酸序列为 与Edman降解法测定的S抗原完全一致 法 S-抗原多肽与 G α-转导蛋白包括霍乱毒素、百日咳毒素和 肠毒素ADP-核糖基化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， 甘露糖 二级结构预测和圆二色谱分析 表明S-抗原具有主要延伸的（β-折叠） 具有小的C-末端螺旋区域的结构。 两人的位置 单克隆抗体结合位点和一个葡萄膜形成位点， 已确定S抗原。 这三个线性免疫原性位点是 位于三个分离位点的20个氨基酸残基内。 的mRNA S抗原的长度约为2kb，存在于视杆细胞中， 在大多数视锥细胞中不存在。 大部分的mRNA被发现 非常接近核，但在肌样组织的大部分中没有发现， 杆内节的椭圆形。 此外，S抗原mRNA存在于 某些类型的松果体细胞。 S抗原在小鼠中只有一个基因， 提示视网膜和松果体的S抗原是相同的。 的 分离人和小鼠的S抗原基因，用部分克隆技术鉴定其S抗原基因。 DNA序列和人S抗原基因位于染色体No. 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.