STRUCTURE AND FUNCTION OF S-ANTIGEN AND ITS GENE

牛视网膜S抗原的互补核酸和基因已被克隆 与世隔绝的，有特点的。从Lambdagt11中分离到cDNA3个克隆 用S多克隆抗血清构建表达文库 用单抗血清进一步验证。观察到的最大的cdna是 500个碱基对的长度。随后用这一方法筛选出来自 Lambdagt10视网膜文库，产生高达900个碱基对的片段 长度。用500个碱基对的cDNA克隆合成的多肽 可被2种不同的单抗识别。相比之下，多肽 由小于400个碱基对的克隆产生的只有 一株单抗。发现500bb的S抗原cDNA. 与信使核糖核酸特异杂交(约1700+200个碱基对) 从牛视网膜和松果体制备而不是从肝脏制备mRNA， 大脑皮层和小脑。用高效液相色谱分离纯化S抗原 测定了N端附近的多肽序列(19个氨基酸)。DNA 用双脱氧法测定了500和900个碱基对的cDNAs序列 方法。900个碱基对的cdna覆盖了来自 羧基末端。从DNA序列推导出的多肽是相同的 与已知的S抗原肽序列一致。S抗原多肽(240 在高产表达细菌系统中表达的氨基酸残基)没有 诱导实验动物葡萄膜炎。 用S抗原和视蛋白探针进行原位杂交分析。 S抗原和视蛋白mRNAs仅检测到视杆细胞内节段和 松果体细胞，而不是锥体细胞。

Complementary DNA (cDNA) and gene for bovine retinal S-antigen have been isolated and characterized. cDNA clones were isolated from a Lambdagt11 cDNA expression library using polyclonal S-antigen antiserum and were further verified using monoclonal antisera. The largest cDNA observed was 500 base pairs long. This was used subsequently to screen cDNA clones from a Lambdagt10 retinal library, yielding fragments up to 900 base pairs in length. Polypeptides synthesized by the 500 base pair cDNA clone was recognized by 2 different monoclonal antibodies. In contrast, polypeptides produced by cDNA clones smaller than 400 base pairs were recognized by only one monoclonal antibody. The 500 base pair S-antigen cDNA was found to hybridize specifically to mRNA (approximately 1700 + 200 base pair) prepared from bovine retina and pineal gland but not to mRNA from liver, cerebral cortex and cerebellum. S-antigen was highly purified by HPLC and determined polypeptide sequence (19 AA) at near N-terminal. The DNA sequences of 500 and 900 base pair cDNA were determined using dideoxy method. 900 base pair cDNA covers the 240 amino acid residues from carboxyl terminal. The polypeptide deduced from DNA sequence is identical in sequence with known S-antigen peptides. The S-antigen polypeptide (240 AA residue) expressed in high yield expression bacterial system did not induce uveitis in the experimental animals. S-antigen and opsin probes were used for in situ hybridization analysis. S-antigen and opsin mRNAs were detected only rod cell inner segments and pinealocytes but not cone cells.