A REVIEW OF PKRRATING

3B). R526 in the loop involving 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 principle chain carbonyl of R413. The idea with the activation phase is stabilized by a hydrogen bond involving Y454 and E480 from αF. f