Figure 6.

BLM stimulates hPOL δ strand displacement activity. (A) Ten nanogram of hPOL δ alone (lane 2) or in the presence of an increasing amount (10, 20 or 50 ng) of BLM (lanes 3–5), PCNA (lanes 7–9) or 50 ng of E. coli RecQ (lane 10) were tested in primer extension assays using the X-poly DNA template as described in Materials and methods section. Eighteen-nucleotide primer was 5′ end labeled. Lane 6 contains 50 ng of BLM alone and shows that BLM does not have DNA polymerase activity. Lane 1: substrate alone; positions of oligonucleotide size-markers are indicated. Schematic representation of the X-poly DNA template is shown. The limit of extension is indicated with the arrow. (B) Quantification of products longer than 34 nt from (A).