Figure 4: The phospho-interaction pattern of β-arrestin-1 was deciphered via the ¹⁹F-NMR spectra.

(a) Effects of different phosphopeptide binding on the ¹⁹F-NMR spectra on β-arrestin-1-F2Y phospho-sensing probes. (b) Specific phospho-binding patterns revealed by ¹⁹F-NMR spectra that correlate to their biochemical and cellular properties. The red balls indicate that a phosphate or a negatively charged residue interacts with the specific phospho-binding site localized in the β-arrestin-1 N terminus. Grey balls indicate that no significant chemical shift increase (Δp.p.m.<0.05) was detected by the phospho-sensor around the specific site. The binding of the seven phosphate sites by V2Rpp promoted both clathrin and SRC binding. Two GRK2pps displayed similar phospho-binding patterns (1-4-6-7) and promoted clathrin binding but not SRC interaction. The phospho-binding pattern for GRK6pp is sites 1 and 5, which may correlate with its SRC function. (c) Effects of binding of GRK6pp mutants on the ¹⁹F-NMR spectra on β-arrestin-1-R7-F2Y and Y63-F2Y phospho-sensing probes. (e) Effects of binding of GRK2pp mutants on the ¹⁹F-NMR spectra on β-arrestin-1 phospho-sensing probes. (d,f) Structural representation of a model of specific interactions between the negative charged GRK6pp/GRK2pp residue and the residue localized in phospho-binding sites of β-arrestin-1. The model was generated by application of the PI-LZerD algorithm using V2Rpp/β-arrestin-1 complex structure (PDB: 4JQI) as a template and adjusted by results from ¹⁹F-NMR spectra.