Salgar S K, Yuan X, Kunz H W, Gill T J
Department of Pathology, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15261, USA.
Immunogenetics. 1997;45(6):353-64. doi: 10.1007/s002510050216.
Five new genes were identified in the growth and reproduction complex (grc) region: RT1.S1, RT1.S2, Rps2r1, Rps2r2, and Rps2r3. The class Ib RT1.S1 and RT1.S2 genes have five distinct exons (1, 4, 5, 6, 7) similar to other class I major histocompatibility complex genes but the conventional exons 2 and 3 are absent. The genes are 97% similar, have CAAT and TATA boxes much upstream of the conventional position, obey the GT/AG rule in their exon-intron boundaries, and are transcribed at a low level in thymus and testis but not in the liver and spleen. The region between exon 1 and exon 4 was analyzed by obtaining transcripts by reverse transcription-polymerase chain reaction (RT-PCR) amplification which revealed the presence of four alternatively spliced mRNA transcripts of RT1.S1: 1) S1-1 (clones 14 and 16) has no exon between exons 1 and 4; 2) S1-2 (clones 7 and 8) has an exon of 45 nucleotides that can translate into 15 amino acids; 3) S1-3 (clone 5) has an exon of 42 nucleotides with a stop codon; and 4) S1-4 (clone 10) has two exons of 42 and 38 nucleotides, respectively, with stop codons. Only one RT1.S2 mRNA transcript was obtained, and it has an exon of 45 nucleotides between exon 1 and exon 4 which can form a peptide identical to the S1-2 isoform for that region. The 45 nucleotide exon between exon 1 and exon 4 was unique for RT1.S1 and RT1.S2 and only matched a sequence in the RT1.O intron region (nucleotides 2905 - 2949). The three ribosomal-protein-S2-related (Rps2r) genes are 94% - 98% similar; they are related to the genes encoding ribosomal protein S2 of the black rat and the LLRep3 genes of the mouse and the human and to the genes encoding Saccharomyces cerevisiae S4, Escherichia coli S5, and other members of prokaryote S5 family. The Rps2r1 gene is located just outside of the grc region. The Rps2r2 and Rps2r3 genes are in the grc and have multiple stop codons in their genomic sequences. The Rps2r1 mRNA transcript was identified by RT-PCR in the thymus and testis but not in the liver and spleen.
在生长与繁殖复合体（grc）区域鉴定出了五个新基因：RT1.S1、RT1.S2、Rps2r1、Rps2r2和Rps2r3。Ib类RT1.S1和RT1.S2基因有五个与其他I类主要组织相容性复合体基因相似的不同外显子（1、4、5、6、7），但缺少传统的外显子2和3。这些基因相似度为97%，在传统位置上游有CAAT和TATA框，在外显子-内含子边界遵循GT/AG规则，在胸腺和睾丸中低水平转录，但在肝脏和脾脏中不转录。通过逆转录-聚合酶链反应（RT-PCR）扩增获得转录本，对1号外显子和4号外显子之间的区域进行分析，结果显示RT1.S1有四种可变剪接的mRNA转录本：1）S1-1（克隆14和16）在1号外显子和4号外显子之间没有外显子；2）S1-2（克隆7和8）有一个45个核苷酸的外显子，可翻译成15个氨基酸；3）S1-3（克隆5）有一个42个核苷酸的外显子，带有终止密码子；4）S1-4（克隆10）分别有两个42和38个核苷酸的外显子，均带有终止密码子。仅获得了一种RT1.S2 mRNA转录本，它在1号外显子和4号外显子之间有一个45个核苷酸的外显子，该区域可形成与S1-2异构体相同的肽。1号外显子和4号外显子之间的45个核苷酸外显子是RT1.S1和RT1.S2所特有的，仅与RT1.O内含子区域（核苷酸2905 - 2949）中的一个序列匹配。三个核糖体蛋白S2相关（Rps2r）基因相似度为94% - 98%；它们与黑鼠核糖体蛋白S2编码基因、小鼠和人类的LLRep3基因以及酿酒酵母S4、大肠杆菌S5和原核生物S5家族的其他成员编码基因相关。Rps2r1基因位于grc区域之外。Rps2r2和Rps2r3基因在grc区域内，其基因组序列中有多个终止密码子。通过RT-PCR在胸腺和睾丸中鉴定出了Rps2r1 mRNA转录本，但在肝脏和脾脏中未鉴定出。
