Lecture 6: Antigen Recognition by B Cell Receptors Flashcards
antibodies are made by
B cells
Antibodies can be ____ or ______
secreted or seated on B cell surface (receptor)
What is the difference between secreted antibodies and antibodies that act as B cell receptors?
Receptors have transmembrane domain. Secreted have hydrophilic tails
The light chain can be either
kappa or lambda
The ____ region engages effector function
constant region
the variable region is the ______ site
antigen binding
disulfide bonds are located between
CH3-CH3
CH1-CL
hinge (CH1, CH2)
What make up the light chain?
VL and CL
The ____ gives the antibody Flexibility
hinge
Where is variability located on the antibody?
1st Ig domain
V and C domains are constructed from two _______
beta sheets
What about basic structure gives variability?
The beta sheet is longer on variable region
What creates the globular Ig domain structure?
Ig fold (beta sandwich)
_____ cuts the disulfide bond between CH1 and CH2
papain
papain results in the following fragments:
Fab, Fab, Fc
____ cleaves AFTER the amino-terminal side
pepsin
pepsin results in fragments:
F(ab)2, pFc
Antibodies can be joined together by a ________
flexible hinge
Which two classes of antibodies do not have a hinge?
IgM, IgE
Which Ig is most abundant?
IgG1
___ is a pentamer
IgM
____ is the first produced after an infection
IgM
___ is secreted into mucosa
IgA
____ exists as a dimer
IgA
Which antibody classes activate classical complement system?
IgM, IgG3, IgG1, IgG2
__ activates alternative complement pathway
IgA1
___ binds to mast cells and basophils (allergic response)
IgE
___ are transferred through placenta
IgG1m IgG2, IgG3, IgG4
The _____ allows IgA and IgM to form polymers
J chain
_________ increases the strength of the interaction between antigen - antibody
Ig polymerization
IgG has high _____
affinity
IgM (as a pentamer) has high _____
avidity
IgM is ___ to respond and has not undergone ________
first; affinity maturation
What are the three function of constant region?
- binding to Fc receptors on immune cells
- Active transport of antibodies (IgA:pIgR and IgG:FcRn)
- activate complements
The function of the antibody involves the (heavy/light/both) chain
heavy
Both the heavy and light chain have three _____ regions and four ______ regions
hypervariable; framework
there are ___ specific regions with high variability each on VH and VL
three
_______ is not distributed equally on Fab
variability
hypervariable regions lie in ________ of folded structure
discrete loops
Antigen binding is facilitated by _______ regions
complementary-determining (CDR)
Antibodies can bind in ____, ____, ____, or ______.
pocket, groove, extended surface, or protruding surface
Antibodies can recognize _____ or ______ epitopes
linear or conformational
_____ epitopes have a more broad response
linear
_____ forces hold together antigen-antibody complex
noncovalent
noncovalent forces examples
electrostatic forces, hydrogen bonds, van der waals, hydrophobic, cation-pi
noncovalent forces can be interrupted by _____
salt concentration, pH change
______ can elute antibodies in the lab via pH/salt disruption
affinity purification
steric hindrance is the concept that
although pathogens have many different epitopes, the binding of one antibody will inhibit the binding of other antibodies that recognize different nearby epitopes due to conformational changes
Which two species don’t have light chains?
camel, shark
How many CH regions do sharks have?
5
