Sequence of a cysteine-rich galactose-specific lectin of Entamoeba histolytica.
Entamoeba histolytica trophozoites adhere to human colonic mucins and epithelial cells by a cell surface galactose-specific lectin. This lectin, which is composed of two subunits linked by disulfide bonds, has been shown to be a protective antigen in an animal model of amebiasis. We have determined the sequence of the mature form of the 170-kDa heavy subunit from cDNA clones and PCR-amplified fragments. The heavy subunit sequence consisted of a putative extracellular domain containing 1209 amino acids with 16 potential sites for N-linked glycosylation, a 26-amino acid hydrophobic region, and a 41-amino acid cytoplasmic tail. The presence of N-linked oligosaccharides was confirmed by culturing amebae with tunicamycin, which resulted in a decrease in the heavy subunit molecular mass to 160 kDa and a loss of lectin activity. The extracellular domain was remarkable for an extensive cysteine-rich domain that shared identify with similar regions of several other cell surface proteins and appeared to confer protease resistance to the subunit.
Mann
B J
BJ
Department of Medicine, University of Virginia, Charlottesville 22908.
Torian
B E
BE
Vedvick
T S
TS
Petri
W A
WA
D000478:Alkylation; D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D003001:Cloning, Molecular; D003545:Cysteine / Q000737:chemistry; D010450:Endopeptidases / Q000494:pharmacology; D004748:Entamoeba histolytica / Q000235:genetics*; D005690:Galactose / Q000378:metabolism; D006031:Glycosylation; D037102:Lectins / Q000235:genetics*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010084:Oxidation-Reduction; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D012995:Solubility
D037102:Lectins; D012333:RNA, Messenger; D010450:Endopeptidases; D003545:Cysteine; D005690:Galactose