The abundance and distribution of terminal aGalNAc was determined using a panel of other lectins. The data indicate that lectins with binding specificities that include terminal aGalNAc (HPA, WFA, VVA-B4) bind to luminal and glandular epithelial cells in both species throughout the cycle. One of the most significant findings of this study was the demonstration in the human endometrium of cryptic binding sites for VVA over the entire surface of the luminal epithelium, in contrast to the highly restricted distribution of DBA-binding loci. buy asthma inhaler
This demonstrates that GalNAc transferases are present, and their absence is unlikely to provide an explanation for the absence of DBA sites in human proliferative and early secretory phases. Furthermore, there are consistent binding sites for DSA, which recognizes the core lactosaminoglycan upon which the blood group A moiety is constructed . The simplest interpretation of the observations is that new terminal oligosaccharides containing the structure GalNAca l,3(Fucal,2)Galpl,4GlcNAcpi appear in human mid-secretory phase glands, and in the late proliferative phase in the baboon. Variation in 1,2 fucosyltransferase activity (rather than aGalNAc transferase) may therefore account for the cycle dependence of expression; production of the blood group A structure requires fucose to be present before aGalNAc can be added . Cyclical variation in the 1,2 fucosyltransferase has been observed in the mouse uterus.