中科院细胞与分子免疫学课程课件3+Antibodies+and+Antigensnew2.ppt
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Section II Recognition of Antigens;;Section II Recognition of Antigens;Chapter 5
Antigen Processing and Presentation to T Lymphocytes
Chapter 6
Antigen Receptors and Accessory Molecules of T Lymphocytes ;Chapter3 Antibodies and Antigens; Natural Distribution and Production of Antibodies;Binding antigen phase:
----In recognition phase
- Membrane antibody function as BCR
Na?ve B cell changed into activated phase
----In effector phase
- Secreted form
Eliminate the antigen;70-kg adult human : 3g of antibodies
Two thirds of the antibody: IgA
Antibodies that enter the circulation have limited half-lives.
----IgG, has a half-life of about 3 weeks.;Molecular Structure of Antibodies ;;Ig domain: about 110 amino acid residues fold independently in a globular motif
Ig super-family: All molecules that contain this motif
; Both the heavy chains and light chains have:
----- N terminal variable regions
in antigen recognition
------ C terminal constant regions
in effector functions;Structural Features of Variable Regions and Their Relationship to Antigen Binding ;Crystallographic analyses of antigen-antibody complexes ;Complementarity-determining regions (CDRs):
Region: The three hypervariable regions of a VL domain and VH domain are brought together in three-dimensional space to form an antigen-binding surface.
Character: a surface complementary to the three-dimensional structure of the bound antigen; Structural Features of Constant Regions and Their Relationship to Effector Functions
;Isotypes: classes
IgG - Gamma (?) heavy chainsγ
IgM - Mu (?) heavy chains μ
IgA - Alpha (?) heavy chains α
IgD - Delta (?) heavy chains δ
IgE - Epsilon (?) heavy chains ε
;Immunoglobulin Isotypes;Subtypes:In humans, IgA and IgG isotypes can be further subdivided into closely related subclasses, or subtypes, called IgA1 and IgA2, and IgG1, IgG2, IgG3, and IgG4. ;Immunoglobulin Allotypes(同种异型);Immunoglobulin Idiotypes(独特型);Antibody molecules
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