Sara - Major Histocompatibility Intro and Structure

Question 1

What is the MHC called in humans?

Answer 1

Human leukocyte antigen

Question 2

Where is the human leukocyte antigen gene located?

Answer 2

The short arm of chromosome 6

Question 3

How many classes of MHC are there?

Answer 3

Three

Question 4

Which classes of MHC are involved in antigen presentation?

Answer 4

Class I and Class II

Question 5

In the HLA region, where is the class I region?

Answer 5

Class I is nearest to the telomere

Question 6

In the HLA region, where is the class II region?

Answer 6

Class II is nearest the centromere

Question 7

In the HLA region, where is the class III region?

Answer 7

Between Class I and Class II

Question 8

What type of genes are class I and class II, how can they be described?

Answer 8

As highly polymorphic genes

Question 9

What are non-polymorphic genes?

Answer 9

Genes represented by only one normal nucleic acid sequence

Question 10

What are polymorphic genes?

Answer 10

Genes where the nucleic acid sequence varies at a relatively high frequency among normal individuals within a population

i.e. there are many different alleles that exist within the population

Question 11

What are alleles?

Answer 11

Each common variant of a polymorphic gene present in the population

Question 12

What cells express MHC Class I?

Answer 12

All nucleated cells

Question 13

What cells express MHC Class II?

Answer 13

Antigen presentating cells

Question 14

What are the three regions of MHC Class I region?

Answer 14

HLA-A
HLA-B
HLA-C regions

Question 15

What does the HLA-A, HLA-B, HLA-C region code for in humans?

Answer 15

The A, B and C molecules of MHC Class I

Question 16

What regions are responsible for Class II in the HLA region?

Answer 16

HLA-DP
HLA-DQ
HLA-DR

Question 17

What does the HLA-DP, HLA-DQ and HLA-DR regions code for?

Answer 17

DP, DQ and DR molecules of class II MHC

Question 18

Class I activate which cells?

Answer 18

CD8+ T lymphocytes (cytotoxic T cells)

Question 19

Class II activate which cells?

Answer 19

CD4+ T lymphocytes (helper cells)

Question 20

What is a MHC haplotype?

Answer 20

The total set of MHC alleles present on each chromsomes

Question 21

What is a MHC haplotype?

Answer 21

The total set of MHC alleles present on each chromosome

Question 22

How many MHC haplotypes does an individual have?

Answer 22

One from the mother and one from the father

Question 23

MHC molecules are part of what family?

Answer 23

Immunoglobulin superfamily

Question 24

What is the MHC groove cleft composed of in Class I?
(2)
Protein structure

Answer 24

2 alpha helical sides

A base of 8 anti-parallel B-pleated sheets

Question 25

What are the four subunits of MHC class I?

Answer 25

a1
a2
a3
B2-microglobulin

Question 26

What two chains make up the MHC class I?

Answer 26

an alpha chain (with three subunits)

A B2 microglobulin

Question 27

What alpha chain subunits form the groove of MHC class I?

Answer 27

a1 and a2

Question 28

How is the B2-microglobulin attached?

Answer 28

It interacts non-covalently with the a chain and has no direct attachment to the cell

Question 29

What are the four regions of class I MHC?

Answer 29

An amino terminal extracellular peptide-binding region (groove/cleft)

An extracellular immunoglobulin-like region

A transmembrane region

A cytoplasmic region

Question 30

What are the two chains of MHC Class II?

Answer 30

a chain
B chain

Question 31

What are the subunits of MHC Class II?

Answer 31

a1
a2
B1
B2

Question 32

What are the four regions of the MHC Class II?

Answer 32

An amino terminal extracellular peptide-binding region - groove/cleft

An extracellular immunoglobulin-like region

A transmembrane region

A cytoplasmic region