Table 1.

Comparison of the peptide sequence around the O-glycosylated Thr⁺¹ of PILRα ligands

	Amino acid position
Ligand	−3	−2	−1	+1	+2	+3	+4	+5	+6	Kd, μM
HSV-1 gB (53-61)	G	P	A	T	P	A	P	P	A	2.3*
mCD99 Thr45 (42-50)	M	K	P	T	P	K	A	P	T	2.8†
mCD99 Thr50 (47-55)	K	A	P	T	P	K	K	P	S	3.3†
PAMP§	G	L	A	T	P	H	P	N	S	Not measured
NPDC1§	L	P	S	T	P	G	T	P	T	0.049‡
COLEC12§	N	E	P	T	P	A	P	E	D	1.1‡

^*The N-terminal region (30–108) of gB was used for the binding study.

^†The single Ala mutation (T45 or T50) did not cause any reduction of PILRα binding compared with mCD99 wild type (K_d = 2.2 μM) (11).

^‡These affinity contained the avidity effect of Fc-fused dimerization (8).

^§These are the predicted O-glycosylation sites of each PILRα ligand.