BIOL 435 Ch. 6 Proteins Involved in V(D)J Recombination

Question 1

RAG1/2 function

Answer 1

• Ag receptor gene recombinase complex
• DNA cleavage mediated by RAG1
• epigentic targeting is directed by RAG2
• lymphoid specific

Question 2

deficiency in RAG1/2

Answer 2

-severe combined immunodeficiency (SCID)

Question 3

terminal deoxyribonucleotidyl transferase (TdT) function

Answer 3

-adds nontemplated (N) nucleotides to V-D and D-J joints of Ig heavy chain
>also all joints of TCR chains in a template independant manner
*lymphoid specific

Question 4

deficiency in TdT

Answer 4

-reduced N-nucleotide addition is seen at coding joints

Question 5

Artemis function

Answer 5

-once phosphorylated by DNA-PKcs, opens the hairpin on the coding end joint

Question 6

deficiency in Artemis

Answer 6

-blocked formation of coding joints and accumulation of hairpin-sealed coding ends

Question 7

Ku 70/80 function

Answer 7

• complex recruited to DNA ds breaks
• stabilizes and aligns DNA ends prior to repair
• essential for repair in both signal and coding joints in Ig and TCR genes

Question 8

deficiency in Ku70/80

Answer 8

-severe combined immunodeficiency (SCID)

Question 9

DNA ligation complex function (DNA ligase IV)

Answer 9

-required for ligation of cut DNA ends (both coding and signal joints)

Question 10

defieciency in DNA ligase IV

Answer 10

-complete block in lymphoid development