Peptides Presented to the Immune System by the Murine Class II Major Histocompatibility Complex Molecule I-A _d

TLDR

The murine MHC class II molecule I‑Ad associates with 650–2000 peptides, all derived from secretory or integral membrane proteins synthesized by the presenting cell. Nine peptide sequences were identified using automated Edman degradation and tandem mass spectrometry; they are 16–18 residues long, possess ragged termini, and contain a six‑residue binding motif positioned variably within the chain. Binding assays of truncated peptides indicate that the class II binding groove can be open at both termini.

Abstract

Between 650 and 2000 different peptides are associated with the major histocompatibility complex class II molecule I-Ad. Sequences for nine of these were obtained by a combination of automated Edman degradation and tandem mass spectrometry. All of the peptides are derived from secretory or integral membrane proteins that are synthesized by the antigen-presenting cell itself. Peptides were 16 to 18 residues long, had ragged NH2-and COOH-termini, and contained a six-residue binding motif that was variably placed within the peptide chain. Binding data on truncated peptides suggest that the peptide binding groove on class II molecules can be open at both ends.