Table 1.

Differences in the binding affinities of major signaling molecules in the TCR-coupled signaling pathway for the ITAMs within the invariant TCR subunits

Signaling Molecule	ITAM Binding Hierarchy	References
ZAP-70	ζ1 ≥ ζ2 > ε ≥ ζ3	Isakov et al. 1995a
	ζ1 = γ = δ > ζ3 > ζ2 = ε	Osman et al. 1996b
	ζ1 > ζ3 > ζ2	Zenner et al. 1996c
Shc	γ = δ > ζ3 = ζ1	Osman et al. 1996
	ζ1> ζ3	Zenner et al. 1996
p85 regulatory subunit of PI3K	ζ3 = γ = δ>ζ1 = ζ2	Osman et al. 1996
	ζ1 ≥ ζ2 > ζ3	Zenner et al. 1996
Grb2	ζ1 = γ = δ	Osman et al. 1996
	ζ2	Zenner et al. 1996
Fyn	ζ2 = γ = δ > ζ1	Osman et al. 1996
Ras-GTPase activating protein (GAP)	ζ2 ≥ ζ1 > ζ3	Zenner et al. 1996

^aAll 3 TCRζ ITAMs and the CD3ε ITAM were tested in this study.

^bAll 6 ITAMs (ζ1, ζ2, ζ3, ε, δ, and γ) were tested in this study. Only the specific ITAMs that physically interacted with the signaling molecule are listed.

^cAll 3 TCRζ ITAMs were tested in this study. Only the specific ζ ITAMs that physically interacted with the signaling molecule are listed.