Flashcards in Generation of receptor diversity Deck (376)
How are the variable regions for heavy and light chains in a mature B cell coded in DNA?
by a single exon-exon 2 but separated from each other within this coding sequence
What is exon 1 of the variable region?
antibody's leader sequence
What is the function of hte antibody's leader sequence?
directs the antibody into the ER for surface expression or secretion
What is the difference between the DNA sequence for the variable-region exon in immature vs mature B cells?
in immature- the exon is encoded by 2 separate DNA segments
How are hte separate DNA segments encoding the varibale region joined together?
spliced together during B cell development in the bone marrow
Which gene segment do CDR1 and CDR2 come from in the immature B cell
variable/V gene segment --also included beta sheets A-F
Which gene segment is CDR3 found in?
partly on V region and rest on J region--as well as beta sheet G
What is the exon encoding the complete variable region formed by the joining of the V and J segments in thel ight chain called ?
What is this rearranemgent of genes in a maturing B cell known as?
somatic DNA recombination
Why does the joining of the V and J segments in the developing B cell also bring hte V gene segment closer to the C segmen/t
J segment is located close to the C region
What separates the J gene segment from the C-region in the rearranged V region?
How many gene segments encode the V region in the heavy chain?
What is the additional gene segment encoding hte V region in the heavy chain?
diversity gene segment
Where is the location of the Dh gene segment in relation to the V and J segments of hte heavy chain?
foudn in between the Vh and Jh segments
What is hte process of recombination for a heavy chain?
2 stages: 1-D and J segments join; then V joins the DJ segment to complete the V region
How are the V regions and C regions joined up?
What creates the great diversity of V regions in immunoglobulin?
there are multiple copies of the V, D and J segments which are combined randomly
What is a pseudogene?
gene segments which aren't functional as have accumulated mutations
Why are there a large number of pseudogenes in hte V, D and J gene segments?
no single gene segment is essential
Which type of light chain has a greater number of unctional genes encoding the V segment?
kappa > lambda
What is the name for the immunoglobulin gene segement clusters?
Which chromosome is the labda light chain locus?
Which hcrosome is the kappar light chain locus found on?
How many constant regions does the kappa light chain have?
How many constant regions does the lambda chain ahve?
one for each joining region-4/5
Which chromosome contains the heavy chain locus?
Waht is the difference between the organisation of hte J segments in relation to the C regions between light and heavy chain?
in the heavy chain the C regions are all clustered together- each corresponding to a different immunoglobulin isotype
How does the expression of other isotypes aside from u and d take place?
thorugh DNA rearragments called class switching (after B cell activation)
what guides DNA rearragments?
conserved noncoding DNA sequences- recombination signal sequences