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30 Cards in this Set
- Front
- Back
B cell generate this segment as they mature
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Antibody gene segment
One VDJ for heavy One VJ for light |
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Transcription of antibody gene segments allows formation of :
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antibody molecules with a single combining site specificity
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"display" the antibody combining site a mature cell can make (allowing them to function in Ab responses)
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B Cell Receptors
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Two components of BCRs
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membrane Ig (mIg) comprised of IgD and IgM monomers
and Ig-alpha/Ig-beta heterodimers |
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Ig-alpha/Ig-beta heterodimers
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disulfide-linked polypeptides containing cytoplasmic domains with ITAMs
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ITAMs
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Immunoreceptor Tyrosine-based Activation Motifs
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change conformation due to mIg cross-linking
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heterodimers
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coexpressed on the surface of naive (virgin) mature B cells
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IgD and IgM monomers
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comprise the N-terminal domains of both heavy and light chains of BCRs
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Variable domains containing three hypervariable (CD) regions
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CDRs in variable domains of surface IgD and IgM bind
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antigenic determinants of native antigen (which initiates capping)
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capping
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cross-linking of BCRs
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comprise the membrane-proximal domains of heavy chains (BCRs)
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constant domains
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transmembrane regions (BCRs)
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stretches of ~20 hydrophobic amino acids) near the C-terminal end of the heavy chains & anchor them (B cell cytoplasmic membranes)
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nearly nonexistent at the C-terminal end of these heavy chains (BCR: IgM/IgG
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cytoplasmic tails
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Generates a signal that is transmitted to the B cell nucleus via an intracellular signal transduction pathway
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ITAM phosphorylation
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# of ITAMS in Igalpha and Igbeta
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alpha: 2
beta: 1 |
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based upon the recruitment of individual B cells, via their ability to specifically interact with an antigenic determinant, into a proliferating population of cells that eventually differentiates
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clonal selection of B cells
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T cells rearrange these segments:
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Surface Receptor Segments
One VJ for alpha One VdJ generated for beta |
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NOT secreted by T cells
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TCRs
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result from their specific interaction with antigen fragments via their TCRs
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T cell proliferation, differentiation and cytokine production
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two components of TCRs
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TCR-alpha/TCR-beta heterodimers
and CD3 |
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comprise the membrane-proximal domains of TCR-alpha and TCR-beta
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constant domain (transmembrane segments and cytoplasmic tails)
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must be coexpressed with the alpha/beta heterodimers (TCRs)
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CD3
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polypeptides comprising CD3
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gamma
delta epsilon (in pairs) zeta (disulfide-linked dimers) |
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link CD3 with the constant regions of alpha/beta herterodimers
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charge-based (electrostatic) interactions
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Zeta and epsilon both have cytoplasmic domains with:
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ITAMS
zeta: 3 episilon: 1 |
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TCR interaction with antigen fragments bound to MHC molecules on APCs initiates
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ITAM phosphorylation by cytoplasmic protein kinases in T cells
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generates a molecular "signal" that is transmitted to the T cell nucleus via an intracellular signal transduction pathway
(TCR) |
ITAM phosphorylation
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based on recruitment of individual T cells, via their ability to specifically interact with an antigenic fragment, into proliferating populations of T cells that eventually differentiates
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clonal selection of t cells
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ACRs used by APCs for presentation of antigen fragments to T cells
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MHCs
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