Fig. 1. GFP-P loop K-A p60 inhibits the in vitro microtubule-severing activity of wild-type p60. Fluorescence images were captured after taxol-stabilized, tetra-methyl rhodamine labeled microtubules were perfused with different protein solutions containing Mg²⁺-ATP, incubated for 4 minutes, then fixed with glutaraldehyde. (A) No katanin. (B) 0.1 µM 6his-wt-p60 pre-bound with 0.1 µM GST-con80. (C) 0.1 µM 6his-wt-p60 pre-bound with 0.1 µM GST-con80 + 0.4 µM GFP-P loop K-A p60. (D) 0.1 µM 6his-wt-p60 pre-bound with 0.1 µM GST-con80 + 0.4 µM heat-inactivated GFP-P loop K-A p60.