Extended Data Fig. 8 |. MS² spectrum of the Ser¹⁴⁸ P phosphopeptide.

(a) One MS² spectrum used for identification of the phosphorylated P peptide ¹⁴²DALDLLS#DNEEEDAESSILTFEER is displayed. Tandem mass spectrum (top) and deviation (bottom) allowed detection of phosphorylation (symbol #) at site Ser¹⁴⁸. Peptides fragmented from the N-terminus (b-fragments) and C-terminus (y-fragments) are colored in blue and red, respectively. (b) y and b ion series m/z identified in the spectrum (a) and their deviation from theoretical m/z are displayed in the Table. The present pattern of phosphorylation agrees with observations showing that phosphorylation of the peptide comprising residues 100–120 (ref 44) of RSV-P - in particular phosphorylation of Thr108 (ref 45) corresponding to Ser148 of HMPV-P (Extended Data Fig. 9)) - controls its interaction with the M2–1 protein.