Semple Jennifer I, Ribas Gloria, Hillyard Guy, Brown Stephanie E, Sanderson Christopher M, Campbell R Duncan
Functional Genomics Group, MRC Rosalind Franklin Centre for Genomics Research, Hinxton, CB10 1SB, Cambridge, UK.
Gene. 2003 Sep 18;314:41-54. doi: 10.1016/s0378-1119(03)00735-2.
The human Major Histocompatibility Complex (MHC) Class III region, which lies in between the MHC Class I and Class II regions on chromosome 6p21.3, contains approximately 60 genes with diverse functions. Using bioinformatics analyses, we identified a novel open reading frame (ORF) in this region, telomeric of BAT1, which we called Mitochondrial Coiled-Coil Domain 1 (MCCD1). The expression of the predicted ORF in a number of human tissues was confirmed by RT-PCR analysis. An orthologue of the MCCD1 gene was identified in the swine MHC in an analogous position, adjacent to pig BAT1. The overall sequence identity between the human and pig MCCD1 proteins is only 65.9%, but their C-terminal domains are highly conserved, showing 92% identity over 53 residues. The MCCD1 gene encodes a short polypeptide (119 amino acids) which contains a putative coiled-coil domain at its highly conserved C terminus and a predicted mitochondrial localisation signal at its N terminus. Transient expression in mammalian cells of MCCD1 fused at its C terminus to either EGFP or the T7-epitope tag showed that this protein is indeed targeted to mitochondria. Finally, we characterised the polymorphism in this gene using denaturing high-performance liquid chromatography (DHPLC) analysis and found that the MCCD1 gene is highly polymorphic containing an average of 1 single nucleotide polymorphism (SNP) every 99 bp. Interestingly, MCCD1 contains four SNPs within the coding region, three of which cause nonsynonymous and nonconservative changes in the amino acid sequence.
人类主要组织相容性复合体（MHC）III类区域位于6号染色体p21.3上的MHC I类和II类区域之间，包含约60个具有不同功能的基因。通过生物信息学分析，我们在该区域BAT1的端粒处鉴定出一个新的开放阅读框（ORF），我们将其命名为线粒体卷曲螺旋结构域1（MCCD1）。通过逆转录聚合酶链反应（RT-PCR）分析证实了预测的ORF在多种人类组织中的表达。在猪的MHC中，在与猪BAT1相邻的类似位置鉴定出了MCCD1基因的直系同源物。人和猪MCCD1蛋白之间的总体序列同一性仅为65.9%，但其C末端结构域高度保守，在53个残基上显示出92%的同一性。MCCD1基因编码一种短多肽（119个氨基酸），其高度保守的C末端含有一个假定的卷曲螺旋结构域，N末端含有一个预测的线粒体定位信号。在哺乳动物细胞中，将MCCD1的C末端与EGFP或T7表位标签融合进行瞬时表达，结果表明该蛋白确实定位于线粒体。最后，我们使用变性高效液相色谱（DHPLC）分析对该基因的多态性进行了表征，发现MCCD1基因具有高度多态性，平均每99个碱基对就有1个单核苷酸多态性（SNP）。有趣的是，MCCD1在编码区内含有4个SNP，其中3个导致氨基酸序列发生非同义且非保守的变化。
