The effect of lipid environment and retinoids on the ATPase activity of ABCR, the photoreceptor ABC transporter responsible for Stargardt macular dystrophy
The effect of lipid environment and retinoids on the ATPase activity of ABCR, the photoreceptor ABC transporter responsible for Stargardt macular dystrophy
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DOI：
10.1074/jbc.m000555200
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发表时间：
2000-07-07
影响因子：
4.8
通讯作者：
Molday, RS
中科院分区：
文献类型：
--
作者：
Ahn, J;Wong, JT;Molday, RS
ABCR是一种光感受器特异性ATP结合盒转运蛋白，其与各种视网膜疾病有关，包括Stargardt黄斑营养不良，并涉及穿过视杆细胞外段（ROS）膜的视网膜转运。我们检测了洗涤剂溶解和重建的ABCR的ATP酶和GT3活性，3-[（3-胆酰胺丙基）二甲氨基]-1-丙磺酸增溶的ABCR具有ATP酶和GT3酶活性（K-m类似于75 μ M; V-max类似于200 nmol/min/mg），其被全反式-视黄醛刺激1.5-2倍并且依赖于磷脂和二硫苏糖醇。重构后ATP的Km降低至接近25 μ M，而V-max强烈依赖于用于重构的脂质。在ROS磷脂中重构的ABCR具有基础和视网膜活化ATP酶活性的V-max，其比在大豆或脑磷脂中的ABCR高4-6倍。这种增强的活性主要是由于活性氧膜上高含量的磷脂酰乙醇胺（PE）。类维生素A刺激的ATP酶活性也需要PE。ABCR的ATP酶活性被N-维A基-PE所刺激，但不被还原衍生物维A基-PE所刺激。在COS-1细胞中表达的ABCR也表现出与天然蛋白相似的视网膜刺激ATP酶活性。这些结果支持ABCR是一种活性视黄酸转运蛋白的观点，其核苷酸酶活性受脂质环境的强烈影响。
ABCR is a photoreceptor-specific ATP-binding cassette transporter that has been linked to various retinal diseases, including Stargardt macular dystrophy, and implicated in retinal transport across rod outer segment (ROS) membranes, We have examined the ATPase and GTPase activity of detergent-solubilized and reconstituted ABCR, 3-[(3-Cholamidopropyl)dimethylammonio]-1-propanesulfonic acid-solubilized ABCR had ATPase and GTPase activity (K-m similar to 75 mu M; V-max similar to 200 nmol/min/mg) that was stimulated 1.5-2-fold by all-trans-retinal and dependent on phospholipid and dithiothreitol. The K-m for ATP decreased to similar to 25 mu M after reconstitution, whereas the V-max was strongly dependent on the lipid used for reconstitution. ABCR reconstituted in ROS phospholipid had a V-max for basal and retinal activated ATPase activity that was 4-6 times higher than for ABCR in soybean or brain phospholipid. This enhanced activity was mainly due to the high phosphatidylethanolamine (PE) content of ROS membranes. PE was also required for retinoid-stimulated ATPase activity. ATPase activity of ABCR was stimulated by the addition of N-retinylidene-PE but not the reduced derivative, retinyl-PE. ABCR expressed in COS-1 cells also exhibited retinal-stimulated ATPase activity similar to that of the native protein, These results support the view that ABCR is an active retinoid transporter, the nucleotidase activity of which is strongly influenced by its lipid environment.