Figure 4

Quantification of Tdk protein levels and stability. Levels of protein were determined by ³⁵S-methionine labeling of whole cells and subsequent immunoprecipitation with polyclonal anti-Tdk antiserum. E. coli KY895 carrying plasmids pTara and pETSTdk (Short-form Tdk) or pETLTdk (Long-form Tdk) was labeled with ³⁵S-methionine for 3 min followed by a chase with excess unlabeled methionine. Samples were removed for processing at 20 s, 2 min and 5 min following the chase and proteins reactive with anti-Tdk serum were immunoprecipitated and separated as described in Methods. Following autoradiography, intensity of the bands corresponding to labeled Tdk were determined and background corrected against a pET-28a(+) vector-only control. The calculated band intensities are expressed in arbitrary units.