A. Dell et al., STRUCTURAL-ANALYSIS OF THE OLIGOSACCHARIDES DERIVED FROM GLYCODELIN, A HUMAN GLYCOPROTEIN WITH POTENT IMMUNOSUPPRESSIVE AND CONTRACEPTIVE ACTIVITIES, The Journal of biological chemistry, 270(41), 1995, pp. 24116-24126
Glycodelin, also known as placental protein 14 (PP14) or progesterone-
associated endometrial protein (PAEP), is a human glycoprotein with po
tent immunosuppressive and contraceptive activities. In this paper we
report the first characterization of glycodelin-derived oligosaccharid
es. Using strategies based upon fast atom bombardment and electrospray
mass spectrometry we have established that glycodelin is glycosylated
at Asn-28 and Asn-63. The Asn-28 site carries high mannose, hybrid an
d complex-type structures, whereas the second site is exclusively occu
pied by complex-type glycans. The major non-reducing epitopes in the c
omplex-type glycans are: Gal beta 1-4GlcNAc (lacNAc), GalNAc beta 1-4G
lcNAc (lacdiNAc), NeuAc alpha 2-GGal beta 1-4GlcNAc (sialylated lacNAc
), NeuAc alpha 2-6GalNAc beta 1-4GlcNAc (sialylated lacdiNAc), Gal bet
a 1-4(Fuc alpha 1-3)GlcNAc (Lewis(x)), and GalNAc beta 1-4(Fuc alpha 1
-3)GlcNAc (lacdiNAc analogue of Lewis(x)). It is possible that the oli
gosaccharides bearing sialylated lacNAc or lacdiNAc antennae may manif
est immunosuppressive effects by specifically blocking adhesive and ac
tivation-related events mediated by CD22, the human B cell associated
receptor. Oligosaccharides with fucosylated lacdiNAc antennae have pre
viously been shown to potently block selectin-mediated adhesions and m
ay perform the same function in glycodelin, The potent inhibitory effe
ct of glycodelin on initial human sperm-zona pellucida binding is cons
istent with our previous suggestion that this cell adhesion event requ
ires a selectin-like adhesion process. This result also raises the pos
sibility that a convergence between immune and gamete recognition proc
esses may have occurred in the types of carbohydrate ligands recognize
d in the human.