一种假定的γ-氨基丁酸（GABA）受体亚基rho2 cDNA的鉴定以及编码rho2（GABRR2）和rho1（GABRR1）的基因在人染色体6q14-q21和小鼠染色体4上的共定位。

Identification of a putative gamma-aminobutyric acid (GABA) receptor subunit rho2 cDNA and colocalization of the genes encoding rho2 (GABRR2) and rho1 (GABRR1) to human chromosome 6q14-q21 and mouse chromosome 4.

作者信息

Cutting G R, Curristin S, Zoghbi H, O'Hara B, Seldin M F, Uhl G R

机构信息

Center for Medical Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland.

出版信息

Genomics. 1992 Apr;12(4):801-6. doi: 10.1016/0888-7543(92)90312-g.

DOI:10.1016/0888-7543(92)90312-g

Abstract

Screening of a genomic DNA library with a portion of the cDNA encoding the gamma-aminobutyric acid (GABA) receptor subunit rho1 identified two distinct clones. DNA sequencing revealed that one clone contained a single exon from the rho1 gene (GABBR1) while the second clone encompassed an exon with 96% identity to the rho1 gene. Screening of a human retina cDNA library with oligonucleotides specific for the exon in the second clone identified a 3-kb cDNA with an open reading frame of 1395 bp. The predicted amino acid sequence of this cDNA demonstrates 30 to 38% similarity to alpha, beta, gamma, and delta GABA receptor subunits and 74% similarity to the GABA rho1 subunit suggesting that the newly isolated cDNA encodes a new member of the rho subunit family, tentatively named GABA rho2. Polymerase chain reaction (PCR) amplification of rho1 and rho2 gene sequences from DNA of three somatic cell hybrid panels maps both genes to human chromosome 6, bands q14 to q21. Tight linkage was also demonstrated between restriction fragment length variants (RFLVs) from each rho gene and the Tsha locus on mouse chromosome 4, which is homologous to the CGA locus on human chromosome 6q12-q21. These two lines of evidence confirm that GABRR1 and newly identified GABRR2 map to the same region on human chromosome 6. This close physical association and high degree of sequence similarity raises the possibility that one rho gene arose from the other by duplication.

摘要

用编码γ-氨基丁酸（GABA）受体亚基rho1的部分cDNA筛选基因组DNA文库，鉴定出两个不同的克隆。DNA测序显示，一个克隆包含来自rho1基因（GABBR1）的单个外显子，而第二个克隆包含一个与rho1基因有96%同一性的外显子。用对第二个克隆中的外显子特异的寡核苷酸筛选人视网膜cDNA文库，鉴定出一个3kb的cDNA，其开放阅读框为1395bp。该cDNA的预测氨基酸序列与α、β、γ和δGABA受体亚基有30%至38%的相似性，与GABA rho1亚基有74%的相似性，表明新分离的cDNA编码rho亚基家族的一个新成员，暂命名为GABA rho2。用来自三个体细胞杂交板DNA的rho1和rho2基因序列进行聚合酶链反应（PCR）扩增，将这两个基因都定位到人类6号染色体q14至q21带。每个rho基因的限制性片段长度变异（RFLV）与小鼠4号染色体上的Tsha位点之间也显示出紧密连锁，该位点与人类6号染色体q12 - q21上的CGA位点同源。这两条证据证实GABRR1和新鉴定的GABRR2定位到人类6号染色体的同一区域。这种紧密的物理关联和高度的序列相似性增加了一个rho基因通过复制从另一个基因产生的可能性。