title: The C-terminal tripeptide of glycosomal phosphoglycerate kinase is both necessary and sufficient for import into the glycosomes of Trypanosoma brucei.
abstract: Glycosomal phosphoglycerate kinase (gPGK) of Trypanosoma brucei differs from the cytoplasmic isozyme (cPGK) in its higher isoelectric point characterized by clusters of positive charges along the polypeptide chain, and a 20 amino acid C-terminal extension ending in serine-serine-leucine (SSL). While a C-terminal SSL tripeptide is apparently not capable of directing luciferase to the peroxisomes in mammalian cells [J. Cell Biol. 108 (1989), 1657-1664], we show here that it is sufficient for the import of luciferase as well as an unrelated protein, beta-glucuronidase, into the glycosomes of T. brucei, as determined by immunoelectron microscopy. The analysis of luciferase-gPGK fusion proteins indicates that the only targeting signal for import of gPGK into the glycosome resides in this C-terminal SSL sequence.
authors.affiliation: Department of Pharmaceutical Chemistry, University of California, San Francisco 94143.
authors.forename: J M
authors.initials: JM
authors.lastname: Sommer
authors.forename: G
authors.initials: G
authors.lastname: Peterson
authors.forename: G A
authors.initials: GA
authors.lastname: Keller
authors.forename: M
authors.initials: M
authors.lastname: Parsons
authors.forename: C C
authors.initials: CC
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D004277:DNA, Single-Stranded; D005966:Glucuronidase / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D008830:Microbodies / Q000201:enzymology*; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D010735:Phosphoglycerate Kinase / Q000737:chemistry / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000201:enzymology* / Q000648:ultrastructure
chemical_list: D004277:DNA, Single-Stranded; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D008156:Luciferases; D010735:Phosphoglycerate Kinase; D005966:Glucuronidase