Effector functions of a mouse IgG that lacks the entire CH1 domain. C1q binding and complement fixation in the absence of antigen.
C1q binding and complement fixation were examined of a short-chain IgG2a antibody that lacks the entire CH1 domain. This short-chain antibody has been reported to have a low level of constitutive complement-activating activity in the absence of Ag. Two-dimensional SDS/PAGE and cation-exchange chromatography have demonstrated that two types of IgG2a proteins are secreted by the short-chain IgG2a antibody producing cell line. It has been shown that 1) the difference between these two types of the IgG2a proteins is whether the two L chains are linked by a disulfide bridge or not, and 2) C1q-binding and complement-activating activities are expressed only when the inter L chain disulfide bridge does not exist. A molecular model is presented for the active form of the short-chain IgG2a antibody.
Mizutani
R
R
Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
Igarashi
T
T
Tanaka
T
T
Shimada
I
I
Arata
Y
Y
D000818:Animals; D001666:Binding Sites, Antibody; D003167:Complement Activation; D015922:Complement C1q / Q000737:chemistry / Q000276:immunology*; D003168:Complement Fixation Tests; D004220:Disulfides; D007127:Immunoglobulin Constant Regions / Q000737:chemistry / Q000502:physiology*; D007074:Immunoglobulin G / Q000737:chemistry / Q000502:physiology*; D007143:Immunoglobulin Heavy Chains / Q000737:chemistry / Q000502:physiology*; D051379:Mice; D017384:Sequence Deletion; D013329:Structure-Activity Relationship
D004220:Disulfides; D007127:Immunoglobulin Constant Regions; D007074:Immunoglobulin G; D007143:Immunoglobulin Heavy Chains; D015922:Complement C1q