A structural motif in the variant surface glycoproteins of Trypanosoma brucei.
The variable domain of the trypanosome variant surface glycoprotein (VSG) ILTat 1.24 has been shown by X-ray crystallography to resemble closely the structures of VSG MITat 1.2, despite their low sequence similarity. Specific structural features of these VSGs, including substitution of carbohydrate for an alpha-helix, can be found in other VSG sequences. Thus antigenic variation in trypanosomes is accomplished by sequence variation, not gross structural alteration; the extensive sequence differences among VSGs may be required for another reason, such as the avoidance of recognition by helper T cells. Additionally, VSG sequences are found to define families, within a VSG superfamily, which have evolved in the trypanosome genome.
Blum
M L
ML
Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, Massachusetts.
Down
J A
JA
Gurnett
A M
AM
Carrington
M
M
Turner
M J
MJ
Wiley
D C
DC
D000595:Amino Acid Sequence; D000818:Animals; D000940:Antigenic Variation; D003198:Computer Simulation; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D016415:Sequence Alignment; D014346:Trypanosoma brucei brucei / Q000737:chemistry* / Q000276:immunology; D014643:Variant Surface Glycoproteins, Trypanosoma / Q000737:chemistry* / Q000145:classification; D014961:X-Ray Diffraction
D014643:Variant Surface Glycoproteins, Trypanosoma