Crystal structures of saposins A and C
Crystal structures of saposins A and C
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DOI：
10.1110/ps.062256606
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发表时间：
2006-08-01
期刊：
影响因子：
8
通讯作者：
Prive, Gilbert G.
中科院分区：
文献类型：
--
作者：
Ahn, Victoria E.;Leyko, Paul;Prive, Gilbert G.
鞘脂激活蛋白A和C分别是半乳糖神经酰胺和葡糖神经酰胺的溶酶体分解所需的鞘脂激活蛋白。鞘脂激活蛋白与脂质相互作用，导致脂质头基对其同源水解酶的可及性增强。我们已经确定了人类saposin A和C的晶体结构，分别为2.0埃和2.4埃，都揭示了紧凑的，单体saposin折叠。我们证实，这两种蛋白质是单体在溶液中的pH值为7.0的分析离心。然而，在pH 4.8时，在洗涤剂C 8 E 5的存在下，saposin A组装成二聚体，而saposin C形成三聚体。鞘脂激活蛋白B在所有测试条件下均为二聚体。saposins的自缔合可能与这些小蛋白质如何与脂质、膜和水解酶相互作用有关。
Saposins A and C are sphingolipid activator proteins required for the lysosomal breakdown of galactosylceramide and glucosylceramide, respectively. The saposins interact with lipids, leading to an enhanced accessibility of the lipid headgroups to their cognate hydrolases. We have determined the crystal structures of human saposins A and C to 2.0 angstrom and 2.4 angstrom, respectively, and both reveal the compact, monomeric saposin fold. We confirmed that these two proteins were monomeric in solution at pH 7.0 by analytical centrifugation. However, at pH 4.8, in the presence of the detergent C 8 E 5, saposin A assembled into dimers, while saposin C formed trimers. Saposin B was dimeric under all conditions tested. The self-association of the saposins is likely to be relevant to how these small proteins interact with lipids, membranes, and hydrolase enzymes.