Lecture 2 - Ab Structure & Fcn Flashcards
(12 cards)
Ab molecules bind to protein, carb, or lipid antigens. T/F
False. Ag’s have only carb and protein components. NOT made up of lipids.
Describe the basic structure of an Ab.
-Two identical light chains
-Two identical heavy chains
-Each light chains is linked to one of the heavy chains via one disulfide bond.
-The heavy chains are attached to eachother through two disulfide bonds, as well.
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Heavy and Light chains are encoded on same gene or separate genes?
Encoded on SEPARATE genes.
Intrachain disulfide bonds help (blank) domains, which are similar but not identical sequences, fold independently.
Immunoglobulin domains
The variable region is at the C-terminus or N-terminus?
N-terminus
Ab’s perform their functions in extracellular spaces, encountering variations in pH, salts concent, proteolytic enzymes, etc. How are they not degraded?
Ab’s have a unique 3* tertiary structer that enables them to withstand this environment.
Beta-barrels form in Ab’s are called _______.
Immunoglobulin folds
Primary difference between C and V domains is:
V domains are LARGER and have an EXTRA LOOP of polypeptide chain.
The flexible loops of V domains form the _____ domain.
Ag-binding domain
Within the variable domains of both light and heavy chains, there are hypervariable regions, also called _______, whih form a single hypervariable site (the Ag-binding site) at the tip of each Ab arm. How many of these are there?
They are also called Complementarity-Determining Regions (CDR) and there are three of these regions:
HV1, HV2, HV3 / CDR1, CDR2, CDR3
Between each HV or CDR region are low variability regions, called ______. How many?
Framework regions.
Four of them, on each light and heavy chain: FR1 - FR4
The region of the Ag that is recognized by the Ab is known as _______ or _______.
Antigenic determinant, or epitope.
