07 - T-cell receptor gene diversity.docx

3 Pages
Unlock Document

Victor Barac

T-cell Receptor Gene Diversity T Cell Receptor (TCR) – Ig superfamily mem+er receptor + – Restricted to CD4 (helper) and CD8 (killer) T lymphocytes – Always membrane bound – Antigen binding domain also contains 2 CDRs  CDR3 is the main antigen contact  CDR1 and CDR2 contact MHC receptors on another cell MHC restriction of T cell recognition T Cell receptor diversity – Generated through the same mechanism as Ig diversity  Involves RAG-1, RAG-2, RSS, all the same enzymes & P- and N- nucleotide addition – TCR α and β chain domains ≈ light chain and heavy chain of Ig  TCR α  V – J – C  TCR β  V – D – J – C [ slightly more variable than α] Gene structure and function of TCR – Variable parts are essentially the same as Ig’s  Shape of antigen binding site is more consistent  CDR1 and CDR2 are less variable  CDR3 is more variable  no somatic hypermutation – Functionally, TCRs only work as cell surface proteins (no secretion)  Don’t actually pass the signal that turns on the T cell themselves (they have assistants)   C domain region of gene is simpler  only 1 Cα and 2 very similar Cβ o No known functional difference – Ig stuff where binding gets better as it binds more doesn’t happen with T cells Combinatorial diversity – TCR covers cellular and humoral immunity  Igs just do humoral  T cells need to do more stuff  need  diversity –  diversity in TCR CDR3 domain is b/c of  combinatorial and jxnal diversity α / β vs. γ / δ TCR + + – All CD4 and CD8 T cells have α / β TCR – Small # of T cells have γ / δ TCR  γ / δ TCR is also a heterodimer  Predicted protein structure of each chain is similar to α / β o i.e. constant domain w/ variable on top  No crystal structure  unsure about ligands  lipids? HSPs? Free ligands? – γ / δ TCR also generated by rearrangement  Fewer V segments than Ig
More Less

Related notes for IMM250H1

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.