The solution conformations of the subclasses of human IgG deduced from sedimentation and small angle X-ray scattering studies.
The solution conformations of human immunoglobulin G subclass molecules have been investigated by sedimentation and small-angle X-ray scattering techniques. Both methods qualitatively indicate IgG3 to be an extended molecule relative to IgG1. Sedimentation data have been collected for a number of paraproteins of all four subclasses and the hinge-deleted IgG1Dob protein. The known crystal structure of Dob allows the use of this protein as a basis for the proposal of models of the average conformations of IgG subclasses which are consistent with experimental s(0)20,w values. IgG1 is suggested to have a hinge length of 0-15 A and non-coplanar Fab arms; IgG2 to be effectively hingeless with folded-back Fab arms; IgG3 to have an extended hinge of the order of 100 A and IgG4 to be effectively hingeless and T-shaped. The possible correlation of these conformations with subclass function is discussed.
Gregory
L
L
Department of Biochemistry, University of Sheffield, U.K.
Davis
K G
KG
Sheth
B
B
Boyd
J
J
Jefferis
R
R
Nave
C
C
Burton
D R
DR
D006801:Humans; D007074:Immunoglobulin G / Q000145:classification*; D008956:Models, Chemical; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D014461:Ultracentrifugation / Q000379:methods; D014961:X-Ray Diffraction
D007074:Immunoglobulin G