The role of the cell surface D-galactose (Gal)/N-Acetyl-D-galactosamine (GalNAc), lectin in the adhesion process has been demonstrated in Entamoeba histolytica, a protozoan parasite that causes amebiasis in humans [1]. The Gal/GalNAc lectin is a heterotrimeric protein complex. It is composed of a 260 kDa heterodimer of trans-membrane disulphide-linked heavy 170 kDa subunit and glycosylphosphatidylinositol (GPI)-anchored light 31 kDa/35 kDa subunits. The light subunits are non-covalently associated with an intermediate subunit of 150 kDa [1] [2]. Inhibition of expression of 35 kDa subunit of Gal/GalNAc lectin inhibits the cytotoxic and cytopathic activity of E. histolytica, but no decrease in adherence capacity to mammalian cells was evident. Interestingly, a carbohydrate-binding activity has been reported for the 35 kDa light subunit of the lectin molecules of the closely related Entamoeba invadens. This entry is related to the light subunit where this domain of unknown function is present. The light subunit consists of several polypeptide chains with considerable antigenic homology. The two light (31/35 kDa) subunits of the lectin are present in two isoforms: the 31 kDa isoform is glycerolphosphatidylinositol (GPI) anchored; and the 35 kDa isoform is more highly glycosylated [2].

1: Biophysical studies on calcium and carbohydrate binding to carbohydrate recognition domain of Gal/GalNAc lectin from Entamoeba histolytica: insights into host cell adhesion. Yadav R, Verma K, Chandra M, Mukherjee M, Datta S; J Biochem. 2016;160:177-186. PMID:27008865

2: Antisense inhibition of expression of the light subunit (35 kDa) of the Gal/GalNac lectin complex inhibits Entamoeba histolytica virulence. Ankri S, Padilla-Vaca F, Stolarsky T, Koole L, Katz U, Mirelman D; Mol Microbiol. 1999;33:327-337. PMID:10411749