Figure 5. The Brix domain is important for binding to single-stranded telomeric DNA.

(A) Schematic representation of the Imp4p domain. The Imp4p is 290 amino acids in length. Sequence analysis reveals a Brix domain located at amino acids 88–275 and a σ⁷⁰-like motif is located at amino acids 245–263. The relative locations of the Brix domain and σ⁷⁰-like motif are indicated. (B) Purification of Imp4p Brix domain and GST. The GST–Brix domain fusion protein and GST protein were purified from E. coli using a glutathione–Sepharose resin (see the Materials and methods section). A 2 μg sample of each of purified Imp4p, GST–Brix and GST was analysed by SDS/12% PAGE and stained with Coomassie Blue. Molecular masses are indicated in kDa. (C) The Brix domain of Imp4p binds to single-stranded TG_1–3 DNA. ³²P-labelled TG40 (5 nM) was mixed with various amounts of GST–Brix or GST and was then analysed by EMSA.