NOT KNOWN DETAILS ABOUT PKRRATING

3B). R526 with the loop between αJ and αI anchors the C-terminal percentage of the activation loop by forming a salt bridge with E458 at the base of αEF. Q459 stabilizes the HRD motif by a hydrogen bond to the most crucial chain carbonyl of R413. The tip on the activation segment is stabilized by a hydrogen bond among Y454 and E480 from αfile.