Flashcards in Receptors Deck (32)
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1
Q
Avidity
A
- Overall bonding of ligand to receptors
Affinity: Strength of a (single) bond
2
Q
ITAM
A
Immuno-receptor Tyrosine Activation Motif
- Recurrent sequence motifs found on many signaling proteins within the immune system
- Contain tyrosines that become phosphorylated following signal transduction through the associated receptor
- Phosphorylation of ITAM-tyrosine residues then allows docking of adapter molecules, thus facilitating initiation of the signaling cascade
3
Q
ITIM
A
Immunoreceptor Tyrosine-based Inhibitory Motif
- Similar in structure to the ITAM motifs
- Mediating inhibitory, rather than activating funcitons
- Activation of B cells results in phosphorylation of the ITIM
4
Q
Lipid Rafts
A
- Highly ordered, detergent-insoluble cholesterol - and sphingolipid-rich membrane regions
- Populated by many molecules critical to receptor signaling
5
Q
NFAT
A
Nuclear Factor of Activated T Cells
- Family of transcription factors
- Includes five members
- Some of which expressed as differentially spliced varients
6
Q
NF-kB
A
- Heterodimeric transcripion factor
- Resting state:
- Held in cytopasm by binding to the Inhibitor of NF-kB (IkB) protein
- Phosphorylation of IkB releases NF-kB into nucleus and binds to the promoters of a whole array of immunologically important genes
7
Q
AP-1
A
- Master transcription factor
- Facilitates the transcription of the IL-2 gene
8
Q
BCR
A
B Cell Receptor
9
Q
Light Chain
A
- Bound to heavy chain by disulfide bond
- Variable region (VL) and Constant Region (CL)
- Two major light chain constant regions
- κ (Kappa)
- λ (Lambda)
10
Q
Heavy Chain
A
- Five major classes of heavy chains
- μ, δ, γ, ε, α
- Each different heavy-chain constant is referred to as an isotype
11
Q
Fab
A
- Functional unit of antibody
- Two identical fragements of the antibody molecule that retain the antigen-binding specificity of the original antibody
12
Q
Fc Region
A
- Identical for all antibodies of a given class
- Crystallizes easily, thus called the Fc region (fragment crystallizable)
13
Q
Kappa
A
- One of the two major light chain constant region sequences
- 60% of human light chains
- If kappa, always kappa
14
Q
Lambda
A
- One of the two major light chain constant regions
- 40% of human light chains
- If lambda, always lambda
- Four subtypes
15
Q
Variable Region
A
- The N-terminal half of the light chain and constant chain
- Changes
- Only about 15 amino acids total that make the difference in variation
- Antigen binding site
16
Q
Constant Region
A
- The less variable part of the sequence (CL)
- Two major light chain constant regions
- κ and λ
17
Q
CDR
A
Complementarity-determining region
- Originally called hypervariable regions
- Regions of hypervariability within the variable regions of the light chain
18
Q
CD21
A
- In BCRs, the CD21 co-receptor, which is associated with CD19, binds to the complement molecule C3d, which binds covalently to the antigen
19
Q
CD19
A
- Contains intracytoplasmic ITAM
- Apart of the CD19/CD21 complex that binds to complement molecules covalently attached to the antigen
20
Q
Iga/IgB
A
- A heterodimer in B cells
- Closely associated with respective antigen receptor and responsible for transitting the signals initiated by ligand binding into the interior of the cell
21
Q
Isotype
A
- Each different heavy-chain constant region is referred to as an isotype
- The isotype of the heavy chains of a given antibody determines its class
22
Q
Allotype
A
- Alternative alelic forms of the same isotype
- Two antibodies with allotypic differences will vary in just a few residues of one of the Ig chains
23
Q
Anti-idiotype
A
- An antibody that binds to the antigen-combining site of another anitbody either suppressing or enhancing the immune response
- Antigenic determinants characteristic of a particular antigen combining site
- Each antibody will have its own characteristic idiotype determinants made up of residues from the heavy and light chains that contribute to the antigen-binding regions
24
Q
TCR
A
T Cell Receptor
25
Q
γδ TCR
A
- Less common than αβ T cells
- At highest abundance in the GALT
- Do not seem to require antigen processing and MHC presentation
26
Q
αβ TCR
A
- TCR
- Binds to MHC-antigen complex but no directcell signaling
- No ITAMs
- Main funcitonal receptor
- Positively charged
27
Q
CD4
A
- a 55 kDa monomeric membrane glycoprotein that cointains:
- four extracellular Ig-like domains (D1-D4)
- a hydrophobic transmembrane region
- a long cytoplasmic tail containing three serine residues that can be phosphorylated
28
Q
CD8
A
- Takes the form of a disulfide-linked αβ heterodimer or αα homodimer
- Both the alpha and beta chains of CD8 are small glycoproteins of approx. 30 to 38 kDa
- Each consist of:
- a single, extracellular, Ig-like domain
- a stalk region
- a hydrophobic transmembrane region
- a cytoplasmic tail containig 25-26 residues
- several of which can be phosphorylated
29
Q
CD3 Complex
A
- Made up of three dimers:
- δε pair
- γε pair
- ζζ pair
- Like Igα/Igβ, the cytoplasmic tails of the CD3 molecules are studded with ITAM sequences
- Serve as docking sites for adapter proteins following activation-induced tyrosine phosphorylation
30
Q
γε
A
- Heterodimer
- Contains two ITAMS
- Negatively charged
- Part of the CD3 complex
31
Q
εδ
A
- Heterodimer
- Contains two ITAMS
- Negatively charged
- Part of the CD3 complex
32
Q
ζζ
A
- Homodimer
- Contains 6 ITAMS
- Negatively charged
- Part of the CD3 complex