title: Molecular cloning of ras and rap genes from Entamoeba histolytica.
abstract: To better understand growth regulation in the protozoan parasite Entamoeba histolytica, ameba genes homologous to the ras oncogene and rap (Krev-1) anti-oncogene were cloned. Two putative ameba ras genes (Ehras1 and Ehras2) were identified, which contain 205 and 203 amino acid (aa) open reading frames (ORFs), respectively. The Ehras1 ORF shows an 91% positional identity with that of Ehras2, a 55% identity with Dictyostelium discoideum (Dd) ras, and a 47% identity with human (Hs) ras. Two ameba rap genes (Ehrap1 and Ehrap2) were identified, both of which contain 184-aa ORFs. The Ehrap1 ORF shows a 93% positional identity with that of Ehrap2, a 60% identity with Dd rap, a 61% identity with Hs Krev-1, and a 45% identity with that of Ehras1. Conserved aa in each ameba ras and rap ORF include GTP-binding sites, effector site, site of ADP-ribosylation by Pseudomonas exoenzyme S, and COOH-terminus CAAX. As all Xs = Leu or Phe, ameba ras and rap proteins may be gerenylgerenylated and not farnesylated. Both ras and rap genes are transcribed by trophozoites. A single 21-kDa ameba ras protein reacts with the rat Y13-259 anti-ras monoclonal antibody, which is located on the cytosolic side of the plasma membrane. These are the first ras and rap genes identified from a protozoan parasite.
authors.affiliation: Department of Tropical Public Health, Harvard School of Public Health, Boston, MA 02115.
authors.forename: P S
authors.initials: PS
authors.lastname: Shen
authors.forename: A
authors.initials: A
authors.lastname: Lohia
authors.forename: J
authors.initials: J
authors.lastname: Samuelson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001483:Base Sequence; D003001:Cloning, Molecular; D004748:Entamoeba histolytica / Q000235:genetics*; D019204:GTP-Binding Proteins / Q000235:genetics* / Q000276:immunology; D017125:Genes, Protozoan; D011905:Genes, ras; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology; D008969:Molecular Sequence Data; D005810:Multigene Family; D016366:Open Reading Frames; D011499:Protein Processing, Post-Translational; D011519:Proto-Oncogenes; D015800:Protozoan Proteins / Q000235:genetics* / Q000276:immunology; D051381:Rats; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D020668:rap GTP-Binding Proteins
chemical_list: D000911:Antibodies, Monoclonal; D008565:Membrane Proteins; D015800:Protozoan Proteins; D019204:GTP-Binding Proteins; D020668:rap GTP-Binding Proteins