Microbiology and Immunology 3300B Lecture : Immunology Notes

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purplejackal117

20 Feb 2012

School

Western University

Department

Microbiology and Immunology

Course

Microbiology and Immunology 3300B

Professor

Rodney Dekoter

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Document Summary

Mhc class ii molecules have an open conformation where longer peptides can fit. They are made of and chains, made of two genes, and each gene has two alleles, and there are many different alleles possible. The 2 and 2 domains are transmembrane domains. The peptide-binding cleft is made of the 1 and 1 domains, but they are not joined by a covalent bond. The peptide-binding groove is open at both ends. Peptide binding to mhc class ii molecules is stabilized by numerous contact points. They bind all along the length of the binding groove, not just at the ends like class i. There are hydrophobic or hydrophilic interactions and hydrogen bonds between the peptide and the mhc molecule. The average peptide binding to class ii molecules is 13-17 amino acid residues (length is not constrained). Anchor residues or contact points lie at various distances from the ends of the peptide. The location is different for every class ii molecule.

Related Questions

True/False:The antibody protein has two functional domains, one variable domain for antigen binding and a second, constant domain to confer specific effector functions. These two functional domains are encoded by the antibody light chain and antibody heavy chain polypeptides, respectively. (1)

True/False: MHC class I molecules generally bind peptides that are 8â10 amino acids. Each allelic variant has preferences for the amino acid residues at key anchor positions, but will not bind every possible peptide containing the correct anchor residues. (1)

Immunology worksheet help?

In people infected with human cytomegalovirus, class I MHC andb2-microglobulin are produced, but very little mature class I MHCis found at the cell surface. Inhibition of which of the followingmolecules by human cytomegalovirus may account for thisphenomenon?

A.	TAP
B.	Ii
C.	TCR
D.	CLIP
E.	RAG

Your chances of having the same MHC haplotype as your siblingare:

A.	1:2.
B.	1:4.
C.	1:16.
D.	1:8.
E.	1:1.

Which of the following is the BEST example of self-MHCrestriction of T cells?

A.	A T-cell clone is deleted when it binds too tightly to selfMHC.
B.	A T-cell clone responds more vigorously to a self-peptide thana foreign peptide.
C.	A T-cell clone recognizes foreign MHC.
D.	A T-cell clone only recognizes foreign peptides when presentedby self MHC.
E.	All of the above

MHC molecules:

A.	are conserved between individuals.
B.	bind repeating patterns found on pathogens.
C.	are recognized by T cells.
D.	are membrane-bound molecules found exclusively on T cells.
E.	are secreted by T cells and bind and neutralize antigen in theserum.

Tasmanian devils are a largely inbred population with littlediversity in the MHC. Which of the following would be a likelyoutcome of this?

A.	They would compensate for low diversity in the MHC with highdiversity in the TCR.
B.	They would compensate for low diversity in the MHC with highdiversity in the BCR.
C.	They would rely only on innate immune responses.
D.	They would be at higher risk of infection.
E.	All of the above

How many different MHC classical class I proteins does eachnucleated cell in a human heterozygous at the MHC locusexpress?

A.	Six
B.	Two
C.	Three
D.	One
E.	None. Only APC express class I.

MHC polymorphisms tend to cluster:

A.	in the peptide-binding groove.
B.	in the transmembrane domain.
C.	in the coreceptor contact residues.
D.	in the framework region.
E.	All of the above

A mutation that renders the MHC class II molecule DMnonfunctional would likely lead to:

A.	cells with no class II MHC.
B.	a deficiency in CD8⁺ T cells.
C.	cells with class II MHC only bound with CLIP.
D.	cells with class II MHC bound with a variety ofself-antigens.
E.	cells with no DO.

The human MHC locus is one of the most polymorphic regions ofthe genome. What does this mean?

A.	This region is regulated by many different mechanisms.
B.	Sequence variability is low in this region.
C.	There are many introns in this region.
D.	There are many different alleles of these genes.
E.	It has the most different genes.

10.

Which of the following is an example ofcross-presentation?

A.	An exogenous peptide being presented on MHC class II
B.	A B-cell antigen being presented to a T cell
C.	An endogenous peptide being presented on MHC class I
D.	An endogenous peptide being presented on MHC class II
E.	An exogenous peptide being presented on MHC class I

magentacamel430

You are examining the binding of a short peptide antigen to the antigen-binding site of an antibody.

The amino acid sequence of the peptide is: Ala-Cys-Phe-Gly-Leu-Val-Pro-His-Gln

The binding site on the antibody is composed of a largely-hydrophobic surface but with the side chains of a lysine residue and an aspartic acid residue oriented towards the cysteine and histidine residues of the peptide antigen respectively.

A) Calculate the average charge on the peptide at pH 7.4 Show your working.

B) Will increasing the pH of the solution containing antigen and antibody from 7.4 to 11 make it easier or harder to dissociate the antigen from the antibody? Explain your answer.

Microbiology and Immunology 3300B Lecture : Immunology Notes

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