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Immunology - Doc Low > Receptors > Flashcards

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:
  1. δε pair
  2. γε pair
  3. 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