MOLELCULAR BIOLOGY OF PHOTOTRANSDUCTION

我们已经鉴定了人和小鼠的S抗原基因， 来自小鼠和人的33-K蛋白基因。 S抗原基因是 长度约50 kbp，包含16个外显子和15个内含子， 内含子占97%，外显子占3%。 基因的5 '侧翼区域， 大约1.5 kbp长，没有已知的调控元件， 转录，如TATA，GC或CCAAT盒。 调控序列和核因子控制组织限制性 研究小鼠arrestin基因的表达。 结果 表明，虽然近端启动子序列-38至+304是足够的， 为了指导低水平的视网膜特异性基因表达， 向上游延伸至位置-209支持更高水平的表达 在视网膜中，以及在透镜、松果体 腺体和大脑。 在位置-205和-185之间的间隔内， 含有六聚体的两个直接重复的区域，TGACCT， 近端启动子结合三个明显的视网膜特异性核因子， - Bp 1、Bp 2和Bp 3--通过中心位于 位置-25和-15。 Bp 1和Bp 3也认识到一个密切相关的 在其他几种脊椎动物的启动子区域中发现的序列 光感受器特异性基因 此外，用于以下的共有结合位点： 指定为PCE 1的Bp 1与已知用于播放 在诱导光感受器特异性基因表达中的关键作用， 果蝇 结果表明，PCE 1和RCS 1是 功能上，以及结构上，相似，尽管显着 果蝇和脊椎动物视觉系统的差异， 参与光感受器特异性基因表达的机制已经被 在进化上非常保守。

We have characterized the S-antigen genes from human and mouse and the 33-K protein genes from mouse and human. The S-antigen genes were approximately 50 kbp in length, contained 16 exons and 15 introns, and comprised 97% intron and 3% exon. The 5'-flanking regions of the genes, approximately 1.5 kbp long, had no known regulatory elements for transcription, such as TATA, GC, or CCAAT boxes. Regulatory sequences and nuclear factors governing tissue-restricted expression of the mouse arrestin gene were investigated. The results showed that, while proximal promoter sequence - 38 to +304 are sufficient to direct low levels of retina-specific gene expression, sequences extending upstream to position -209 support higher levels of expression in the retina, as well as detectable expression in the lens, pineal gland, and brain. Within the interval between positions -205 and -185, a region which contains two direct repeats of the hexamer, TGACCT, the proximal promoter binds three apparently retina-specific nuclear factors- -Bp1, Bp2, and Bp3--through overlapping sequences centered between positions -25 and -15. Bp1 and Bp3 also recognize a closely related sequence found in the promoter regions of several other vertebrate photoreceptor-specific genes. Moreover, the consensus binding site for Bp1, designated PCE1, is identical to RCS1, an element known to play a critical role in eliciting photoreceptor-specific gene expression in Drosophila melanogaster. The results suggest that PCE1 and RCS1 are functionally, as well as structurally, similar and that, despite marked differences in the fly and vertebrate visual system, the transcriptional machinery involved in photoreceptor-specific gene expression has been strongly conserved evolutionarily.