Dramatic changes in ER shape and curvature occur in the absence of Rtns/Yop1. (A) 3D model of ER in a wt cell with a 665-nm bud and a 1,255-nm bud that were overlayed to show the transition of ER domains into the bud. (B) As in A for corresponding mutant cells. Note the loss of membrane curvature throughout the mother of both mutant cells. However, the ER is still inherited by an Rtn/Yop1-independent process into the bud. Bars, 200 nm.