title: Nucleotide sequence of the Paramecium primaurelia G surface protein. A huge protein with a highly periodic structure.
abstract: The complete DNA sequence of the G surface protein of Paramecium primaurelia has been determined. It contains an open reading frame of 8145 nucleotides devoid of introns and coding for a protein of 329,000 Mr. Analysis of the deduced amino acid sequence reveals remarkable features such as important internal homologies and a periodic structure, which could be dictated in part by the rigid scaffolding of cysteine residues. The predicted secondary structure shows a quasi absence of alpha-helix and an abundance of beta-pleated sheets and random coils. The monotony of the amino acid sequence is in favour of a structural role for the protein. Interestingly, homologies with other proteins are limited to surface antigens of trypanosomes. Finally, our data are consistent with a genetic code for paramecium which differs from the "universal" code by the assignment of TAA and TAG codons to glutamine.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics*; D000954:Antigens, Surface / Q000235:genetics; D001483:Base Sequence; D003062:Codon; D004247:DNA / Q000235:genetics; D005796:Genes; D005815:Genetic Code; D010247:Paramecium / Q000235:genetics*; D011487:Protein Conformation; D015800:Protozoan Proteins; D012689:Sequence Homology, Nucleic Acid
chemical_list: D000596:Amino Acids; D000953:Antigens, Protozoan; D000954:Antigens, Surface; D003062:Codon; D015800:Protozoan Proteins; C043323:immobilization antigens; D004247:DNA