Expression cloning and characterization of a novel glycosylphosphatidylinositol-anchored high density lipoprotein-binding protein, GPI-HBP1
Expression cloning and characterization of a novel glycosylphosphatidylinositol-anchored high density lipoprotein-binding protein, GPI-HBP1
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DOI：
10.1074/jbc.m211932200
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发表时间：
2003-02-28
影响因子：
4.8
通讯作者：
Yamamoto, TT
中科院分区：
文献类型：
--
作者：
Ioka, RX;Kang, MJ;Yamamoto, TT
通过使用荧光标记的高密度脂蛋白（HDL）的表达克隆，我们分离出两个克隆，赋予HDL的细胞表面结合。核苷酸序列分析表明，其中一个克隆对应于清道夫受体B类1型（SRBI），另一个克隆编码一种新的228个氨基酸的蛋白质。新鉴定的HDL结合蛋白的一级结构类似于GPI锚定蛋白，其由N-末端信号序列、具有天冬氨酸和谷氨酸残基簇的酸性区域、在淋巴细胞抗原家族中高度保守的Ly-6基序和C-末端疏水区域组成。这种新鉴定的HDL结合蛋白命名为GPI锚定的HDL结合蛋白1（GPI-HBP 1），对磷脂酰肌醇特异性磷脂酶C处理敏感，并以高亲和力结合HDL（计算的Kd = 2-3 μ g/ml）。与SRBI类似，GPI-HBP 1介导选择性脂质摄取，但不介导HDL的蛋白组分。在SRBI的各种配体中，HDL最优先与GPI-HBP 1结合。与SRBI相反，GPI-HBP 1缺乏HDL依赖性胆固醇流出。GPI-HBP 1转录本在心脏中检测到最高水平，在肺和肝脏中检测到的水平要低得多。原位杂交显示GPI-HBP 1转录物在心肌细胞、肝枯否细胞和窦内皮细胞以及肺中的支气管上皮和肺泡巨噬细胞中积累。
By expression cloning using fluorescent-labeled high density lipoprotein (HDL), we isolated two clones that conferred the cell surface binding of HDL. Nucleotide sequence of the two clones revealed that one corresponds to scavenger receptor class B, type 1 (SRBI) and the other encoded a novel protein with 228 amino acids. The primary structure of the newly identified HDL-binding protein resembles GPI-anchored proteins consisting of an N-terminal signal sequence, an acidic region with a cluster of aspartate and glutamate residues, an Ly-6 motif highly conserved among the lymphocyte antigen family, and a C-terminal hydrophobic region. This newly identified HDL-binding protein designated GPI-anchored HDL-binding protein 1 (GPI-HBP1), was susceptible to phosphatidylinositol-specific phospholipase C treatment and binds HDL with high affinity (calculated K-d = 2-3 mug/ml). Similar to SRBI, GPI-HBP1 mediates selective lipid uptake but not the protein component of HDL. Among various ligands for SRBI, HDL was most preferentially bound to GPI-HBP1. In contrast to SRBI, GPI-HBP1 lacked HDL-dependent cholesterol efflux. The GPI-HBP1 transcripts were detected with the highest levels in heart and, to a much lesser extent, in lung and liver. In situ hybridization revealed the accumulation of GPI-HBP1 transcripts in cardiac muscle cells, hepatic Kupffer cells and sinusoidal endothelium, and bronchial epithelium and alveolar macrophages in the lung.