Burgess D L, Gefrides L A, Foreman P J, Noebels J L
Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA.
Genomics. 2001 Feb 1;71(3):339-50. doi: 10.1006/geno.2000.6440.
The CACNG1 gene on chromosome 17q24 encodes an integral membrane protein that was originally isolated as the regulatory gamma subunit of voltage-dependent Ca2+ channels from skeletal muscle. The existence of an extended family of gamma subunits was subsequently demonstrated upon identification of CACNG2 (22q13), CACNG3 (16p12-p13), and CACNG4 and CACNG5 (17q24). In this study, we describe a cluster of three novel gamma subunit genes, CACNG6, CACNG7, and CACNG8, located in a tandem array on 19q13.4. Phylogenetic analysis indicates that this array is paralogous to the cluster containing CACNG1, CACNG5, and CACNG4, respectively, on chromosome 17q24. We developed sensitive RT-PCR assays and examined the expression profile of each member of the gamma subunit gene family, CACNG1-CACNG8. Analysis of 24 human tissues plus 3 dissected brain regions revealed that CACNG1 through CACNG8 are all coexpressed in fetal and adult brain and differentially transcribed among a wide variety of other tissues. The expression of distinct complements of gamma subunit isoforms in different cell types may be an important mechanism for regulating Ca2+ channel function.
位于17q24染色体上的CACNG1基因编码一种整合膜蛋白，该蛋白最初是作为骨骼肌中电压依赖性Ca2+通道的调节性γ亚基被分离出来的。随后，在鉴定出CACNG2（22q13）、CACNG3（16p12 - p13）以及CACNG4和CACNG5（17q24）后，证实了γ亚基存在一个扩展家族。在本研究中，我们描述了位于19q13.4上呈串联排列的三个新的γ亚基基因簇，即CACNG6、CACNG7和CACNG8。系统发育分析表明，该基因簇分别与位于17q24染色体上包含CACNG1、CACNG5和CACNG4的基因簇是旁系同源的。我们开发了灵敏的逆转录聚合酶链反应（RT-PCR）检测方法，并检测了γ亚基基因家族（CACNG1 - CACNG8）各成员的表达谱。对24种人体组织以及3个解剖后的脑区进行分析发现，CACNG1至CACNG8在胎儿和成人脑中均有共表达，且在多种其他组织中的转录存在差异。不同细胞类型中γ亚基异构体不同组合的表达可能是调节Ca2+通道功能的重要机制。
