TCR Complex Signal Transduction
When a T cell meets an antigen presenting cell...
– You need lots of TCRs engaging MHCs to get a signal need SMAC composed of...
TCRs and co-receptors to clustered on one side of the cell stimulated by antigen recognition
Integrins surrounding the TCR + co-receptor zone
o They bind the APC complement integrins to seal the two cells together
– Stages of T cell activation:
Membrane events: seconds
Cytoplasmic events: minutes
Novel gene transcription: hours
Immunoreceptor Tyrosine Activation Motif (ITAM)
– Present on cytoplasmic tail of many cell surface receptors that pass signals
– 2 tyrosines (Y) separated by 9 – 12 aas
Y X X [L/V] X6–9 Y X X [L/V] X = any aa, L = leucine, V = valine
– Phosphorylated by Src family kinases
Ex// Lck, Blk, Fyn, Lyn
– Recognized by another kinase family with SH2 (Src homology 2) domains
1. Resting T cell ITAMs not phos.
Fyn bound to cytoplasm