Table 2.

Glycosylation inhibitors

Inhibitor and effective sites	Expected structure	Percent decrease in 5-HT uptake rates of trophoblasts
PNGase F cleaves between the innermost GlcNAc and asparagine residues from N-linked glycoproteins	Nascent SERT (no glycosylation)
Endoglycosidase H cleaves the bond between two GlcNAc subunits, N-acetylglucosamine residue remaining on the asparagine (46).	GlcNAc- SERT
Tunicamycin, a competitive inhibition of UDP-GlcNAc, prevents the glycosyl modification at initial step (46).	Nascent SERT (no glycosylation)	35–72.3%
		Significant (P value <0.001)
Castanospermine, α-glucosidase inhibitor, prevents removal of the glucose residues (46).	Glc3Man9GlcNAc2-SERT	28.7%
		Not significant (P value = 0.02)
Swainsonine inhibitor of Golgi mannosidase II (46).	Man5GlcNAc2-SERT	7.8%
		Not significant (P value = 1.54)