Extended Data Fig. 8 | Identification of GRK5 phosphorylation sites in
human NTSR1 and comparison of phosphate-specific contacts in NTSR1–
βarr1(ΔCT) to those in Rho–Arr1 and V2Rpp–βarr1. a, Snake diagram of
human NTSR1 showing identified phosphosites in ICL3 and the receptor C
terminus. The trypsin/LysC digestion sites are shown in light blue. All four
phosphosites for ICL3 are in a single peptide beginning with QA A at the end of
TM5 and ending at PGR at the beginning of TM6. Phosphosites in the C terminus
occur on two peptides, one containing S396, RPAFSR, as well as several missed
cleavage variants; and one containing S401, S403, S404, T407 and T413.
Tabulated fragment ions are presented in Supplementary Tables 8–39 and
spectra are shown in Supplementary Figs. 2–5. Any post translational
modifications outside of these two discussed regions are not shown for clarity.
These experiments were performed independently twice, and analysed by two
or three technical replicates each time, all with similar results. b, Overlay of
arrestin structures, in which binding of phosphorylated receptor residues
contributes to stabilizing the active state of arrestin. Left, equivalent
phosphoresidues on different receptor C-tails (shown in stick representation
and coloured accordingly: NTSR1, yellow; V2Rpp, red; rhodopsin, pink)
contribute to arrestin activation by interacting with a lysine residue on the gate
loop (K294, shown as Cα spheres), thereby breaking the polar core. Right,
phosphoresidue pT347 in the V2Rpp interacts with residue K77 at the base of
the finger loop. A similarly positioned phosphoresidue in the ICL3 of NTSR1
(pS287) probably interacts with arrestin residues R76/K77 in a similar manner.