PIP<sub>2</sub> Interacts Electrostatically with MARCKS-like Protein-1 and ENaC in Renal Epithelial Cells
oleh: Qiang Yue, Otor Al-Khalili, Auriel Moseley, Masaaki Yoshigi, Brandi Michele Wynne, Heping Ma, Douglas C. Eaton
| Format: | Article |
|---|---|
| Diterbitkan: | MDPI AG 2022-11-01 |
Deskripsi
We examined the interaction of a membrane-associated protein, MARCKS-like Protein-1 (MLP-1), and an ion channel, Epithelial Sodium Channel (ENaC), with the anionic lipid, phosphatidylinositol 4, 5-<i>bis</i>phosphate (PIP<sub>2</sub>). We found that PIP<sub>2</sub> strongly activates ENaC in excised, inside-out patches with a half-activating concentration of 21 ± 1.17 µM. We have identified 2 PIP<sub>2</sub> binding sites in the N-terminus of ENaC β and γ with a high concentration of basic residues. Normal channel activity requires MLP-1’s strongly positively charged effector domain to electrostatically sequester most of the membrane PIP<sub>2</sub> and increase the local concentration of PIP<sub>2</sub>. Our previous data showed that ENaC covalently binds MLP-1 so PIP<sub>2</sub> bound to MLP-1 would be near PIP<sub>2</sub> binding sites on the cytosolic N terminal regions of ENaC. We have modified the charge structure of the PIP<sub>2</sub> –binding domains of MLP-1 and ENaC and showed that the changes affect membrane localization and ENaC activity in a way consistent with electrostatic theory.