Three-dimensional structure of low density lipoproteins by electron cryomicroscopy.
Human low density lipoproteins (LDL) are the major cholesterol carriers in the blood. Elevated concentration of LDL is a major risk factor for atherosclerotic disease. Purified LDL particles appear heterogeneous in images obtained with a 400-kV electron cryomicroscope. Using multivariate statistical and cluster analyses, an ensemble of randomly oriented particle images has been subdivided into homogeneous subpopulations, and the largest subset was used for three-dimensional reconstruction. In contrast to the general belief that below the lipid phase-transition temperature (30 degrees C) LDL are quasi-spherical microemulsion particles with a radially layered core-shell organization, our three-dimensional map shows that LDL have a well-defined and stable organization. Particles consist of a higher-density outer shell and lower-density inner lamellae-like layers that divide the core into compartments. The outer shell consists of apolipoprotein B-100, phospholipids, and some free cholesterol.
Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030, USA.
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EV
Orlova
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MB
Sherman
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W
Chiu
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Mowri
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LC
Smith
A M
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Gotto
D020285:Cryoelectron Microscopy; D005615:Freezing; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008077:Lipoproteins, LDL / Q000097:blood* / Q000648:ultrastructure*; D008297:Male; D008958:Models, Molecular; D010316:Particle Size; D013696:Temperature
D008077:Lipoproteins, LDL