Contains T Cell α-Chain

Contains B Cell Heavy Chain

Contains T Cell δ-Chain

V and J Segments Only.

Has One C Region.

D and J.

Then V and DJ.

Has Two C Regions.

RAG Genes

CD3 Complex Proteins

Composed of an α:β Chain

Helps Signal into cell:

CD3 Complex (CD3ε, CD3δ on one end. CD3γ, CD3ε on other end). With two ζ chains below.

4 Domains with a hinge between 3 and 2

An Alpha chain (heavy chain) of three parts.

Alpha 3 is connected to membrane and is the part that binds to coreceptor CD8.

A Beta₂ Microglobulin.

An 2 Alpha and 2 Beta Chains on the membrane.

Coreceptor CD4 binds to Beta₂.

Bind peptides hydrophobic or basic of 8-10 amino acids because peptides are bound by their ends.

8 antiparallel Beta sheets and 2 antiparallel Alpha helices.

CDR3 binds to peptide. Others to Alpha Helices.

Binds peptides along length between 13-25 amino acids long.

8 antiparallel Beta sheets and 2 antiparallel Alpha helices.

CDR3 binds to peptide. Others to Alpha Helices.

Immunoproteasome

(MHC I Only)

IFN-Gamma induces its change.

LMP2, LMP7, & PA28 binds and helps activate it.

Makes peptides with hydrophobic or basic residue.

Transports peptides into E.R. from cytosol.

Composed of TAP-1 and TAP-2.

1. Calnexin holds Alpha chain shape.

2. Beta₂ binds and calnexin is released.

3. Peptide Loading Complex forms.

4. [Self] Peptides are sampled in binding site.

5. Leave E.R. in vesicle to Golgi.

Peptide Loading Complex

(MHC I Only)

Tapasin binds to TAP-1 and MHC Alpha 3.

ERp57 binds to tapasin.

PDI which binds to ERp57 and MHC Alpha 2.

Calreticulin replaces calnexin.

E.R. Aminopeptidase

(MHC I Only)

Invariant Chain

(MHC II Only)

Binds to MHC II and prevents binding of peptides in the E.R.

Deliver MHC II to vesicles called MHC II Compartments.

The invariant chain is clipped into a small fragment that covers binding site.

Removed by HLA-DM to allow sampling of peptides. HLA-DM removes weak peptides also.

Encodes HLA molecules.

Class I Region: 6 HLA Class 1 genes

Class II Region: All HLA Class 2 genes

Class III Region/ Central MHC: Other genes

Class I has 6 isotypes.

Class II has 5 isotypes.

Ranges within population: Highly polymorphic, Polymorphic, Oligomorphic, & Monomorphic.

MHC I isotype

Present antigens to CD8 T Cells and interact with NK cells.

MHC I isotypes

Interact with NK cells.

MHC I isotype

Function is unknown

Activator that is induced by TNF-Gamma.

Induces expression of HLA-DM, HLA-DP, HLA-DQ, HLA-DR, and invariant chain.

Amino acids that complement peptide and anchor it to the MHC.

Peptide binding motifs are many anchor residues that define the MHC binding places.

MHC I usually has it at positions 2 and 9.

T Cells interact with only certain amino acids and Alpha Helices of MHC molecules.

Some are incompatible even though peptide is compatible.