FIGURE 5.

Effect of STAS domain on OASTL activity. OASTL activity was measured after co-incubation with SULTR1;2STAS, SULTR1;2LSTAS, SULTR1;1STAS, and SULTR1;1LSTAS, all fused to MBP (MBP-1;2STAS, MBP-1;2LSTAS, MBP-1;1STAS, and MBP-1;1LSTAS), as well as with free MBP. OASTL was added at 0.5 ng/μl, and the STAS-MBP fusions were added to the reaction mixtures at the indicated molar ratios (OASTL:MBP molar ratio were 1:1, 1:7, 1:12, as shown in black, unfilled, and gray bars, respectively). Asterisks demarcate values judged to be significantly different based on Student's t tests: *, p = 0.002; **, p = 0.005 (n = 3–5).