ITAMs

Question 1

ITAM stands for

Answer 1

Immunoreceptor Tyrosine-Based Activation Motif

Question 2

what are ITAMS

Answer 2

Antigen receptors, Fc receptors and some of the activating receptors of natural killer cells

Question 3

ITAMS signal via

Answer 3

a common mechanism that is dependent on a conserved amino-aci sequence motif

Question 4

the conserved amin-acid sequence motif is known as

Answer 4

ITAM

Question 5

ITAM contains

Answer 5

2 precisely spaced tyrosine within a consensus sequence

Question 6

when phosphorylated

Answer 6

the tyrosine’s provide a binding site for one or to closely related intracellular tyrosine kinases

Question 7

which intracellular tyrosine kinases are provided a bindings site on the ITAM?

Answer 7

SYK in most immune cells

ZAP-70in T cells

Question 8

both Syk and ZAP-70 have

Answer 8

tandem SH2 domains (src homology 2) evenly spaced at exactly the right distance apart to cock onto the two phosphotyrosines which activate signalling events downstream of the receptor

Question 9

signal transduction by ITAM-containing immunoreceptors

Answer 9

1) The surface immunoglobulin (Ig)that serves as the B cell receptor for antigen brings the receptor into proximity with a Src-family tyrosine kinase, which is held in the plasma membrane by a lipid tail and phosphorylates ITAM tyrosines in the receptor Iga and Igb chains
2) This creates a binding site for Syk, which binds to the doubly phosphorylated ITAM sequence
3) Once bound, Syk becomes activated by tyrosine phosphorylation and it then phosphorylates other signaling proteins that ultimately bring about changes in the behaviour of the cell e.g. antibody production