(A) A conserved basic patch at the N-terminal end of Efr3 mediates complex association with the plasma membrane. The Efr3 C terminus and Stt4/PI4KIIIα both interact with the C-terminal portion of Ypp1. As yet, no function has been assigned to conserved surfaces at the middle of Efr3-N or in the Ypp1 N-terminal half.
(B) Stt4/PI4KIIIα recruitment to the plasma membrane is reduced when the Efr3 C terminus is phosphorylated to interrupt the Efr3-Ypp1 interaction. P indicates that the Efr3 C terminus is heavily phosphorylated in vivo.