HEXB基因编码β-己糖胺酶B亚基,属于溶酶体酶家族中的己糖胺酶基因家族(HEX基因家族)。该家族包括HEXA、HEXB和HEXDC三个成员,共同特点是编码溶酶体水解酶,参与糖脂和糖蛋白的降解代谢。HEXB与HEXA基因产物形成β-己糖胺酶A(Hex A)和β-己糖胺酶B(Hex B)两种异源二聚体酶,其中Hex A由α(HEXA编码)和β(HEXB编码)亚基组成,Hex B则由两个β亚基组成。这些酶主要作用于神经节苷脂GM2和其他含有N-乙酰己糖胺的底物,在溶酶体中发挥关键的分解作用。HEXB基因突变会导致β亚基功能缺陷,影响Hex A和Hex B的活性,造成GM2神经节苷脂在神经元中异常积累,引发常染色体隐性遗传病Sandhoff病(GM2神经节苷脂沉积症Ⅱ型)。该病表现为进行性神经退化,症状包括肌张力减退、运动障碍、癫痫和早夭。HEXB过表达可能通过增强溶酶体降解能力而具有神经保护作用,但具体机制尚不明确;而表达降低则直接导致酶活性不足引发Sandhoff病。HEXB与HEXA存在功能互补性,当HEXA突变导致Tay-Sachs病时,HEXB的正常表达可部分代偿Hex A功能。该基因位于人类5号染色体(5q13.3),包含14个外显子,其启动子区域含有多个转录因子结合位点。目前针对HEXB相关疾病的研究集中在基因治疗、酶替代治疗和底物减少疗法等方面。
Hexosaminidase B is the beta subunit of the lysosomal enzyme beta-hexosaminidase that, together with the cofactor GM2 activator protein, catalyzes the degradation of the ganglioside GM2, and other molecules containing terminal N-acetyl hexosamines. Beta-hexosaminidase is composed of two subunits, alpha and beta, which are encoded by separate genes. Both beta-hexosaminidase alpha and beta subunits are members of family 20 of glycosyl hydrolases. Mutations in the alpha or beta subunit genes lead to an accumulation of GM2 ganglioside in neurons and neurodegenerative disorders termed the GM2 gangliosidoses. Beta subunit gene mutations lead to Sandhoff disease (GM2-gangliosidosis type II). Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, May 2014]
氨基己糖苷酶B是溶酶体酶的β-氨基己糖苷酶,与辅因子GM2激活蛋白一起,催化神经节苷脂GM2和含有末端N-乙酰氨基己糖的其它分子的降解的β亚基。的β-氨基己糖苷酶是由两个亚单位,α和β,这是由单独的基因编码的。两者的β-氨基己糖苷酶的α和β亚基是糖基水解酶家族20的成员。在α或β亚基基因突变导致GM2神经节苷脂在神经元的积累和神经退行性疾病称为GM2 gangliosidoses。 β亚基基因突变导致桑德霍夫病(GM2-神经节苷脂II型)。已发现该基因编码不同亚型选择性剪接转录变异体。 [由RefSeq的,2014年5月提供]
HEXB基因(以及对应的蛋白质)的细胞分布位置:
HEXB基因的本体(GO)信息:
| 名称 |
|---|
| 520 Amino sugar and nucleotide sugar metabolism [PATH:hsa00520] |
| 531 Glycosaminoglycan degradation [PATH:hsa00531] |
| 603 Glycosphingolipid biosynthesis - globo series [PATH:hsa00603] |
| 604 Glycosphingolipid biosynthesis - ganglio series [PATH:hsa00604] |
| 511 Other glycan degradation [PATH:hsa00511] |
| 4142 Lysosome [PATH:hsa04142] |
| 名称 |
|---|
| Chondroitin sulfate/dermatan sulfate metabolism |
| CS/DS degradation |
| Glycosaminoglycan metabolism |
| Glycosphingolipid metabolism |
| Hyaluronan metabolism |
| Hyaluronan uptake and degradation |
| Keratan sulfate degradation |
| Keratan sulfate/keratin metabolism |
| Metabolism |
| Metabolism of carbohydrates |
| Metabolism of lipids and lipoproteins |
| Sphingolipid metabolism |
| 疾病名称 | 关系值 | NofPmids | NofSnps | 来源 |
| Sandhoff Disease | 0.46005048 | 35 | 13 | BeFree_CLINVAR_CTD_human_GAD_LHGDN_MGD_UNIPROT |
| Infantile Sandhoff Disease | 0.240542884 | 2 | 1 | BeFree_CLINVAR_ORPHANET |
| Juvenile Sandhoff Disease | 0.120542884 | 2 | 0 | BeFree_ORPHANET |
| Adult Sandhoff Disease | 0.12 | 0 | 0 | ORPHANET |
| Acute kidney injury | 0.12 | 1 | 0 | CTD_human |
| IGA Glomerulonephritis | 0.12 | 1 | 0 | CTD_human |
| Sandhoff Disease, Adult Type | 0.12 | 0 | 2 | CLINVAR |
| Sandhoff Disease, Juvenile Type | 0.12 | 0 | 2 | CLINVAR |
| Sandhoff Disease, Infantile Type | 0.12 | 0 | 1 | CLINVAR |
| Tay-Sachs Disease | 0.003452799 | 4 | 0 | BeFree_GAD |
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