Mutations in NPC1 highlight a conserved NPC1-specific cysteine-rich domain
Mutations in NPC1 highlight a conserved NPC1-specific cysteine-rich domain
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DOI：
10.1086/302620
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发表时间：
1999-11-01
影响因子：
9.8
通讯作者：
Neumann, PE
中科院分区：
文献类型：
--
作者：
Greer, WL;Dobson, MJ;Neumann, PE
尼曼-匹克II型疾病是一种常染色体隐性遗传疾病，其特征是细胞内固醇运输缺陷。我们已经确定了8个外显子的内含子/外显子边界从保守的3'部分的NPC 1，基因与大多数情况下的疾病。SSCP分析被设计用于这些外显子，并用于确定大多数突变在13个明显无关的家庭。发现13个突变，占26个等位基因中的13个。这些突变包括8种不同的错义突变（包括Greer等人[1998]报道的一种）、1种产生提前终止密码子的4-bp和2种产生提前终止密码子的2-bp缺失，以及2种预计会改变剪接的内含子突变。两个错义突变存在于预测的跨膜（TM）结构域。这些和其他报道的NPC 1突变在羧基末端三分之一的蛋白质的聚类表明，这些外显子的筛选，通过这里报道的SSCP分析，将检测到大多数突变。Npc 1蛋白的羧基末端的一半与形态发生素受体Patched的TM结构域具有氨基酸相似性，其中最大的一段不相关序列位于两个假定的TM跨度之间。这部分的人Npc 1蛋白序列与Npc 1相关的序列从小鼠，酵母，线虫，和植物，Arabinopsis的比对，揭示了保守的半胱氨酸残基，可能协调这个结构域的结构。总共13个NPC 1错义突变中的7个集中在这个单一的NPC 1特异性结构域中，这表明该区域的完整性对于蛋白质的正常功能特别重要。
Niemann-Pick type II disease is an autosomal recessive disorder characterized by a defect in intracellular trafficking of sterols. We have determined the intron/exon boundaries of eight exons from the conserved 3' portion of NPC1, the gene associated with most cases of the disease. SSCP analyses were designed for these exons and were used to identify the majority of mutations in 13 apparently unrelated families. Thirteen mutations were found, accounting for 13 of the 26 alleles. These mutations included eight different missense mutations (including one reported by Greer et al. [1998]), one 4-bp and two 2-bp deletions that generate premature stop codons, and two intronic mutations that are predicted to alter splicing. Two of the missense mutations were present in predicted transmembrane (TM) domains. Clustering of these and other reported NPC1 mutations in the carboxy-terminal third of the protein indicates that screening of these exons, by means of the SSCP analyses reported here, will detect most mutations. The carboxy-terminal half of the Npc1 protein shares amino acid similarity with the TM domains of the morphogen receptor Patched, with the largest stretch of unrelated sequence lying between two putative TM spans. Alignment of this portion of the human Npc1 protein sequence with Npc1-related sequences from mouse, yeast, nematode, and a plant, Arabinopsis, revealed conserved cysteine residues that may coordinate the structure of this domain. That 7 of a total of 13 NPC1 missense mutations are concentrated in this single Npc1-specific domain suggests that integrity of this region is particularly critical for normal functioning of the protein.