Figure 3: Proposed model for regulation of NHE1 activity by 4.1R80 in erythrocytes. Schematic representation of the lipid bilayer and NHE1-4.1R80 interaction, involving the motifs M1 (K513KKQETKR) and M2 (R556FNKKYVKK,) in NHE1 cytoplasmic domain and the EED motif in 4.1R FERM domain. Competition between 4.1R and PIP2 for binding to NHE1 as a function of Ca2+/ CaM concentration is depicted [60].