Williams David L, Wong Jinny S, Hamilton Robert L
Department of Pharmacological Sciences, University Medical Center, State University of New York, Stony Brook, NY 11794, USA.
J Lipid Res. 2002 Apr;43(4):544-9.
Scavenger receptor class B type I (SR-BI) mediates the selective uptake of HDL cholesteryl ester into liver and steroidogenic tissues. In steroidogenic cells, juxtaposed microvilli, or microvilli snuggled against the plasma membrane create microvillar channels that fill with HDL. Microvillar membranes contain SR-BI and are believed to be the site of HDL cholesteryl ester uptake. A recent study showed that SR-BI expression in insect cells elicits membrane structures that contain SR-BI, bind HDL, and closely resemble the ultrastructure of microvillar channels. In the present study we compared the ultrastructure of adrenal gland microvillar membranes in Srb1+/+ and Srb1-/- mice to test whether SR-BI is required for the formation of microvillar channels. The results show that SR-BI is absolutely required for microvillar channel formation and that the microvillar membranes of Srb1-/- mice are 17% thinner than in Srb1+/+ mice. We conclude that SR-BI has a major influence on plasma membrane ultrastructure and organization in vivo.
I型清道夫受体B类（SR-BI）介导高密度脂蛋白胆固醇酯选择性摄取到肝脏和类固醇生成组织中。在类固醇生成细胞中，并列的微绒毛，或紧贴质膜的微绒毛形成充满高密度脂蛋白的微绒毛通道。微绒毛膜含有SR-BI，被认为是高密度脂蛋白胆固醇酯摄取的部位。最近一项研究表明，昆虫细胞中SR-BI的表达引发了含有SR-BI、结合高密度脂蛋白且与微绒毛通道超微结构极为相似的膜结构。在本研究中，我们比较了Srb1+/+和Srb1-/-小鼠肾上腺微绒毛膜的超微结构，以测试微绒毛通道的形成是否需要SR-BI。结果表明，微绒毛通道的形成绝对需要SR-BI，且Srb1-/-小鼠的微绒毛膜比Srb1+/+小鼠的薄17%。我们得出结论，SR-BI对体内质膜的超微结构和组织有重大影响。
