The serine-rich Entamoeba histolytica protein is a phosphorylated membrane protein containing O-linked terminal N-acetylglucosamine residues.
Previously, we described the isolation of a cDNA clone and the gene encoding a protective antigen of the protozoan parasite Entamoeba histolytica, the serine-rich Entamoeba histolytica protein (SREHP). The derived amino acid sequence of the SREHP cDNA clone was remarkable for a high serine content (52/233 amino acids), a putative signal sequence, multiple hydrophilic dodecapeptide and octapeptide tandem repeats, and a hydrophobic C-terminal putative membrane-spanning region. Here, we show that SREHP is modified by the addition of phosphate at serine residues, O-linked terminal N-acetylglucosamine residues, and by acylation. When the SREHP gene is expressed in baculovirus transformed Sf-9 cells, the product is also phosphorylated and glycosylated and is localized to the plasma membrane of the insect cells. The native SREHP molecule also serves as a potent chemoattractant for amebic trophozoites. The data presented here suggest that SREHP is a unique membrane protein with phosphorylation and glycosylation patterns usually associated with nuclear or cytoplasmic proteins.
Stanley
S L
SL
Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
Tian
K
K
Koester
J P
JP
Li
E
E
D000117:Acetylglucosamine / Q000032:analysis*; D000215:Acylation; D000595:Amino Acid Sequence; D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D001483:Base Sequence; D002478:Cells, Cultured; D002630:Chemotactic Factors; D003001:Cloning, Molecular; D017931:DNA Primers; D004748:Entamoeba histolytica / Q000378:metabolism*; D004952:Esters; D006031:Glycosylation; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018411:Spodoptera
D002630:Chemotactic Factors; D017931:DNA Primers; D004952:Esters; D008565:Membrane Proteins; D015800:Protozoan Proteins; C073020:serine-rich protein, Entamoeba histolytica; D000117:Acetylglucosamine