PLRG1 is a evolutionarily conserved protein in spliceosome and plays an important role in maintaining the integral part of the splicoeosme and its proper splicing. Here we solved the high resolution crystal structure of the WD40 domain of human PLRG1 by crystallography and compared our crystal structure with the cryo-EM structure of PLRG1 bound with other splicing factors. We found that two loops of the WD40 domain become resolved upon binding to the proteins within the spliceosome. Thus our work characterize the dynamic property of PLRG1 during the spliceosome assembly by presenting its apo structure. (C) 2020 Elsevier Inc. All rights reserved.