Trypanosoma cruzi glycosomal glyceraldehyde-3-phosphate dehydrogenase does not conform to the 'hotspot' topogenic signal model.
The genes which encode glycosomal glyceraldehyde-phosphate dehydrogenase (gGAPDH) of Trypanosoma cruzi are arranged as a tandemly repeated pair on a single chromosome and are identical at the level of nucleotide sequence. They are separated by an intergenic region which contains a 317 base pair sequence with the properties of a retroposon. The genes express a 1.5 kb mRNA and a 38 kd protein. The amino acid sequence contains features characteristic of glycosomal enzymes such as peptide insertions and a C-terminal extension. However, T. cruzi gGAPDH lacks one of the positively charged 'hotspot' motifs which have been proposed as topogenic signals for import into the glycosome, a unique microbody-like organelle. Molecular modelling of the T. cruzi and T. brucei enzymes suggests that neither structure would fulfil the requirements of the 'hotspot' glycosomal import model.
Kendall
G
G
Department of Medical Parasitology, London School of Hygiene and Tropical Medicine, UK.
Wilderspin
A F
AF
Ashall
F
F
Miles
M A
MA
Kelly
J M
JM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D004251:DNA Transposable Elements; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics*; D007438:Introns; D008958:Models, Molecular; D008969:Molecular Sequence Data; D005810:Multigene Family; D015388:Organelles / Q000201:enzymology; D011487:Protein Conformation; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D015398:Signal Transduction; D014349:Trypanosoma cruzi / Q000201:enzymology / Q000235:genetics*
D004251:DNA Transposable Elements; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases