L3 Late phase activation

Question 1

why is Ca (release) signal required?

Answer 1

without Ca signal no Tc activation. (If Calcineurin is inhibited = no Tc division)

Question 2

What are the 3 major pathways in the activation of Tc

Answer 2

1. [Ca2+]
2. PKC
3. Ras/ Rac (CD28)
   all lead to expression of DNA

Question 3

describe [Ca2+] pathway for activation of Tc

Answer 3

Ca binds Calmodulin: activates calcineurin (phosphatase). P removed from NFATc -> translocate to nucleus = NFATn: transcription factor.

Question 4

describe PKC pathway for activation of Tc

Answer 4

PKC P inhibitory subunit: Ikb allow dissociation of NF-kb -> & enter nucleus

Question 5

describe Ras/Rac pathway for activation of Tc

Answer 5

GTP binds & Ras/Rac activates series of kinases for cell mitogens 
- activates 1. MAP-K & 2.JNK
1. MAP-K P fos: converts to 
   transcription factor 
2. JNK P jun -> nucleus 
1/2. fosJun associate: AP-1 =   
       modulation of gene 
       expression

Question 6

Summary of major signal activation pathways summary

Answer 6

Soluble signal > kinase/phosphatase > transcription factor > translocated of transcription factor
(for soluble signal to enter nucleus it must be deP)

Question 7

Name transcription gene phases

Answer 7

1. intermediates genes: fos, c-myc
2. early genes: IL2, Il2Ra, cytokine
3. Late MHC, adhesion molecules, VLA

Question 8

Describe Bc activation

Answer 8

binding of complement tagged antigen allows antigen to bind to CD21 (CR2) cell surface.
this induces CD19 & CD81 (TAPA-1)
crosslinking & clustering of the co-receptor w/ the antigen = P of Y in ITAMS (Iga/B)
scr family P Y in CD19.
P ITAMS in Iga/B reruit & activate Y kinase Syk. -> PLC etc.