FIG 1.

VSG genes are located mostly at subtelomeric regions in the T. brucei genome. (A) Large subtelomeric VSG arrays, including both VSG genes and pseudogenes. (B) Individual VSG genes often are found on minichromosomes at subtelomeric regions. (C) A typical VSG expression site (ES). VSG is the last gene in any ES and is located within 2 kb of the telomere repeats. A long stretch of 70-bp repeats is upstream of the VSG gene. ESs also contain a number of ESAG genes, which are upstream of the 70-bp repeats. The ES promoter is often 40 to 60 kb upstream of the VSG gene. ESs are located on megabase and intermediate chromosomes.