B Cell Receptor - Fatchiyah – Molecular Biology

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MEMBRANE RECEPTOR FOR
ANTIGEN
Kelompok : 4
Ninda Sahriyani
(105090100111010)
Ganys Tri S.
(115090107111020)
Agatha Mia
(115090101111010)
Vita Agustina
(115090100111011)
Jurusan Biologi
Fakultas Matematika dan Ilmu pengetahuan Alam
Universitas Brawijaya
2013
THREE LIMBS OF IMMUNE RESPONE
Fig 1. Three Limbs Immune Respone
Major Histocompatability Complex
(MHC)
• Group of genes that code for proteins that
found on the surfaces of cells that help the
immune
system
recognize
foreign
substances
• Also known as HLA (Human Leukocyte
Antigen)
Two types:
Class I
Class II
• Found in every nucleated
cell
• Bound to cytotoxic T cell
(CD8)
• Found in special cell such
as macrophage, dendritic
cell, B cell, and thymus
• Bound to Helper T cell
Function of MHC
1. Determinate between the self and
nonself antigens
2. Presenting antigen to T cells
3. Determinate interaction between
B cells, T cells and other cells.
Degradation Process (Processing and
Presentation) Antigen
There are 3 ways of processing and
presentation antigens :
1. Protein from extracellular pathogen broken
down and processed by exogen pathway
2. Protein from self-protein and virus protein
processed by endogen pathway
3. Lipid and derivate processed like extracelular
protein and endosom, with CD1, that similiar
to MHC and presented to CD8 T cell.
Function of MHC
Fig 2. MHC Structures
TABLE 1. DIFFERENCES BETWEEN CLASS I
AND CLASS II MHC
Variable
Bound to
Class I MHC
CD8 T cell
Enzyme to form Cytosolic protease
peptide
Class II MHC
CD4 T cell
Endosome and lysosom
protease
Peptide binding
site in cell
Reticulum endoplasmic
Vesicle specialized
compartment
Peptide size
8-9 amino acid
13-17 amino acid
Expression and
Presentation
• Expressed to
hematopoietic cells
• Presented by all nucleated
cells.
• Expressed to
hematopoietic cell and
stromal cell at thymus
• Presented by
macrophage, dendritic
cell, B cell
SIMILARITIES OF ANTIGEN PRESENTING
BY MHC MOLECULES
• Presented to T cell on the surface of APC
(Antigen Presenting Cell)
• Every MHC can only bind to single antigen
fragment at one time, at the peptide
binding cleft
• The presented antigen fragment is only
amino acid chain
• The binding is done intracellular
Fig 2. Class I MHC Antigen Presenting Pathway
Fig 3. Class II MHC Antigen Presenting Pathway
T Cell Receptor (TCR)
T
• Mature T cell have thousands identical
receptor on the cell surface
• 2 kinds of receptor:
–Alpha/beta (αβ) chain T cell (95%)
–Gamma/delta (γδ) chain T cell (5%)
• Co-receptor : CD4 and CD8
T Cell Receptor Complex: TCR-CD3
Fig 5. TCR-CD3
• TCR binding to MHC-antigen
• The long cytoplasmic tail of the CD3 functions in signal transduction.
Role of co-receptors in TCR binding
affinity
Fig. 6 Role of co- receptor
CD 4 and CD8 : they may act as adhesion molecule helping the T cell
bind to the APC during antigen presentation for duration that is
sufficient for antigen recognition or act as signal transducers.
THANK YOU FOR YOUR ATTENTION…
ANY QUESTION???
VIDEO
Link :
T Cell Dependent Antigens
http://highered.mcgraw-hill.com/olc/dl/120
110/micro33.swf
Cytotoxic T Cell
http://highered.mcgrawhill.com/olc/dl/120110/micro34.swf

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