Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
Cell Rep. 2023 Jun 27;42(6):112609. doi: 10.1016/j.celrep.2023.112609. Epub 2023 Jun 7.
We applied raw human liver microsome lysate to a holey carbon grid and used cryo-electron microscopy (cryo-EM) to define its composition. From this sample we identified and simultaneously determined high-resolution structural information for ten unique human liver enzymes involved in diverse cellular processes. Notably, we determined the structure of the endoplasmic bifunctional protein H6PD, where the N- and C-terminal domains independently possess glucose-6-phosphate dehydrogenase and 6-phosphogluconolactonase enzymatic activity, respectively. We also obtained the structure of heterodimeric human GANAB, an ER glycoprotein quality-control machinery that contains a catalytic α subunit and a noncatalytic β subunit. In addition, we observed a decameric peroxidase, PRDX4, which directly contacts a disulfide isomerase-related protein, ERp46. Structural data suggest that several glycosylations, bound endogenous compounds, and ions associate with these human liver enzymes. These results highlight the importance of cryo-EM in facilitating the elucidation of human organ proteomics at the atomic level.
我们将未经处理的人肝微粒体裂解物应用于有孔碳网格，并使用冷冻电镜（cryo-EM）来确定其组成。从这个样本中，我们鉴定并同时确定了十种参与不同细胞过程的独特人肝酶的高分辨率结构信息。值得注意的是，我们确定了内质双功能蛋白 H6PD 的结构，其 N-和 C-末端结构域分别独立具有葡萄糖-6-磷酸脱氢酶和 6-磷酸葡萄糖酸内酯酶的酶活性。我们还获得了异源二聚体人 GANAB 的结构，这是一种内质网糖蛋白质量控制机制，包含一个催化α亚基和一个非催化β亚基。此外，我们观察到一个十聚体过氧化物酶 PRDX4，它直接与一种二硫键异构酶相关蛋白 ERp46 接触。结构数据表明，几种糖基化、结合的内源性化合物和离子与这些人肝酶结合。这些结果突出了 cryo-EM 在促进人类器官蛋白质组学在原子水平上阐明方面的重要性。
