Figure 6.

Zinc Promotes TAG1 Binding to DNA.

(A) Effect of added zinc on DNA binding. Approximately 60 μg of BL21-expressed ΔC-133 derivative was loaded onto two lanes of an 8% SDS-PAGE gel, electrophoresed, and transferred to a nitrocellulose filter as described in Methods. After Ponceau S staining, the filter was cut into two pieces, and half was processed with 1 mM ZnCl₂ added to all buffers (preincubation, hybridization, and wash; see Methods), whereas the other half was processed without added zinc. Filters were probed with ∼35 ng of ³²P-labeled 5′ STR DNA, washed, and exposed to film at −80°C for 20 min.

(B) Immunoblot of the ΔC-133 derivative. Immunodetection of polypeptides present on the filters in (A) was performed after removal of the probe, using a 1:5000 dilution of affinity-purified αNTG1 antibodies.