A stable, multi-subunit complex of beta2glycoprotein I.
Beta2glycoprotein I (beta2GPI) is a 54-kDa plasma protein which is recognized as an autoantigen for antibodies from patients with antiphospholipid syndrome (APS). SDS-PAGE (under reducing conditions) of beta2GPI from three sources indicates that the 54-kDa beta2GPI band is accompanied by a band corresponding to an 8-kDa protein. In the absence of detergent and reducing agents (native PAGE), beta2GPI demonstrated a large complex (molecular mass approximately 320 kDa) which is dissociable by boiling in 6-8 M urea, yielding several lower molecular mass bands, one of which corresponds to the 8-kDa protein observed in SDS-PAGE. Sera from five healthy adults demonstrated native beta2GPI migration equivalent to the commercially purified protein. Atomic force microscopy (AFM) images of native beta2GPI show aggregrates of particles each having a diameter of 30-35 nm. This is consistent with a globular unit the size of which would be substantially larger than that expected for a 54-kDa protein. These experiments suggest that the 54-kDa beta2GPI monomer subunits exist as a multimeric complex with the 8-kDa protein.
Department of Chemistry, College of Arts and Sciences, School of Graduate Medical Education, Seton Hall University, South Orange, New Jersey, USA.
M
M
Galazka
L B
LB
Keil
J D
JD
Kohles
J
J
Li
S P
SP
Kelty
M
M
Petersheim
V A
VA
DeBari
D000328:Adult; D015153:Blotting, Western; D003902:Detergents / Q000494:pharmacology; D004220:Disulfides / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D006023:Glycoproteins / Q000097:blood / Q000737:chemistry* / Q000187:drug effects; D006801:Humans; D018625:Microscopy, Atomic Force; D008970:Molecular Weight; D011487:Protein Conformation; D019163:Reducing Agents / Q000494:pharmacology; D012967:Sodium Dodecyl Sulfate; D053482:beta 2-Glycoprotein I
D003902:Detergents; D004220:Disulfides; D006023:Glycoproteins; D019163:Reducing Agents; D053482:beta 2-Glycoprotein I; D012967:Sodium Dodecyl Sulfate