Probably plays a crucial role in the binding of the barbed end of actin filaments to the plasma membrane. A head-to-tail association, of the N-terminal and C-terminal halves results in a closed conformation (inactive form) which is incapable of actin or membrane-binding. Interacts with CPNE1 (via VWFA domain) and CPNE4 (via VWFA domain). Binds SLC9A3R1. Interacts with NHERF1, NHERF2, LAYN, MME/NEP and ICAM2. Interacts (via FERM domain) with SPN/CD43 cytoplasmic tail (By similarity). Interacts with CD44 (By similarity). Highly concentrated in the undercoat of the cell-to-cell adherens junction and the cleavage furrow in the interphase and mitotic phase, respectively. The N-terminal domain interacts with the C-terminal domain of LAYN. An interdomain interaction between its N-terminal and C-terminal domains inhibits its ability to bind LAYN. In the presence of acidic phospholipids, the interdomain interaction is inhibited and this enhances binding to LAYN (By similarity). Phosphorylated by tyrosine-protein kinases. Phosphorylation by ROCK2 suppresses the head-to-tail association of the N-terminal and C-terminal halves resulting in an opened conformation which is capable of actin and membrane-binding (By similarity).