L2 T cell membrane

Question 1

define ITAM & give sequence

Answer 1

Immunoreceptor Tyrosine Activation Motifs

YL-*6-8-YL

Question 2

Describe src family kinases

Answer 2

SH2: 100 a.a long / Tyr-P docking
SH3: proline docking 60 a.a kinase catalytic subunit
R (regulatory subunit)

Question 3

Describe syk family kinases

Answer 3

x2 SH2 domains

kinase catalytic subunit

Question 4

Describe lck after dephosphorization by CD45

Answer 4

- opens up due to 
  dephosphorization via 
  CD45.
- SH2 regions allow docking 
  of phosphorylated Y 
- Phosphorylated Y (aa505) 
  keeps inactive 
- CD45 contacts aa505 -> 
  removes P on Y (1st step in 
  Tc activation) 
- opens lck protein 
- catalytic subunit Y is P (aa394) 
  = catalytic energy

Question 5

when CD4 binds MHC-II on APC what is recruited

Answer 5

Lck is recruited to the Tc receptor complex

Question 6

what factor is Tc activation dependent on

Answer 6

Spatial proximity