Extended Data Fig. 5: Analysis of insulin peptides secreted from islets upon glucose challenge.
From: Pancreatic islets communicate with lymphoid tissues via exocytosis of insulin peptides
a, Insulin secretion assay was performed as described in Fig. 3a–c, except that protease inhibitors were added during the 25-mM glucose challenge. The supernatants were then collected for the competitive ELISA assay. Data are mean ± s.e.m. from two independent experiments. b, Mass spectra of four secreted peptides that contain the B:12–20 and/or B:13–21 epitopes as listed in Fig. 3e. Secreted B:1–30 sequences are identical to those in Extended Data Fig. 3a, and B:9–23 and B:11–23 share identical sequences with those in Extended Data Fig. 3b. c, A mass spectrum of the secreted insulin B:15–23 MHC-I (Kd)-binding peptide. d, A mass spectrum of the secreted insulin A:14–20 MHC-I (Db)-binding peptide. e, A mass spectrum showing a representative B–C-spanning peptide (B25–C23).
