Send to

Choose Destination
Cell. 1995 Nov 17;83(4):555-61.

A developmentally regulated position effect at a telomeric locus in Trypanosoma brucei.

Author information

Laboratory of Molecular Parasitology, Rockefeller University, New York, New York 10021-6399, USA.


Trypanosoma brucei undergoes antigenic variation in the mammalian host. This can be achieved by activation and inactivation of telomeric variant-specific surface glycoprotein genes (vsg). In procyclic (insect midgut stage) cells, Vsg is not expressed. The mechanisms that regulate transcription of vsg expression sites (ESs) are unknown. Here we demonstrate that transcription from three different promoters was repressed when they were inserted at a transcriptionally silent telomere-proximal locus in bloodstream-form cells. This position effect was stable and heritable. Only transcription from an ES promoter was repressed in procyclic cells. The observed position effect and the promoter-specific developmental regulation suggest that these phenomena reflect the mechanisms that regulate vsg expression.

[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center