Updated project metadata. PELP1 is a scaffold protein with diverse cellular functions including its role as the central scaffold for the human Rix1 complex (PELP1, WDR18, TEX10, and SENP3). We have reconstituted the mammalian Rix1 complex and identified a sub-complex made of the conserved Rix1 domain of PELP1 and the WDR18 protein. Moreover, using Cryo-electron microscopy (cryo-EM) and aided by chemical crosslinking and mass spectrometry, we determined the structure of this PELP1 Rix1 domain complexed with WDR18.