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Summary

Title

HLA-B40-peptidome

Description

HLA class I molecules bind peptides derived from the intracellular degradation of endogenous proteins and present them to cytotoxic T lymphocytes, allowing the immune system to detect transformed or virally infected cells. It is known that endogenous HLA class I associated peptides may harbor posttranslational modifications. In particular, phosphorylated ligands have raised much interest as potential targets for cancer immunotherapy. By combining affinity purification with high resolution mass spectrometry, we identified more than 2000 unique ligands associated to HLA-B40. Sequence analysis revealed two major anchor motifs: Aspartic or glutamic acid at peptide position 2 (P2) and methionine, phenylalanine or aliphatic residues at the C-terminus. The use of IMAC and TiO2 affinity chromatography allowed the characterization of 86 phosphorylated ligands. Every sequence belonging to this subset was further confirmed by comparing its experimental MS2 spectrum with that obtained upon fragmentation of the corresponding synthetic peptide. Remarkably, three of the identified phospholigands lacked a canonical anchor residue at P2 containing phosphoserine instead. Binding assays showed that this sort of peptides bound to HLA-B40 with high affinity probably due to the molecular mimicry between these residues. Altogether, our data demonstrate that the peptide repertoire of a given HLA allotype can be broadened by the presentation of peptides with posttranslational modifications at major anchor positions. We suggest that ligands with phosphorylated residues at P2 may be optimal targets for T-cell based cancer immunotherapy.

Sample Processing Protocol

See details in reference(s) : 24366607

Data Processing Protocol

See details in reference(s) : 24366607

Contact

Miguel Marcilla, Proteomics Unit - Dpt. of Macromolecular Structures - Spanish National Biotechnolgy Centre (CNB-CSIC)

Submission Date

04/09/2013

Publication Date

03/02/2014

Disease

lymphoma

Quantification

Not available

Experiment Type

Bottom-up proteomics

Assay count

1

Publication

    Marcilla M, Alpizar A, Lombardia M, Ramos-Fernandez A, Ramos M, Albar JP. Increased Diversity of the HLA-B40 Ligandome by the Presentation of Peptides Phosphorylated at Their Main Anchor Residue. Mol Cell Proteomics. 2013 Dec 23 PubMed: 24366607

Assay

Showing 1 - 1 of 1 results
# Accession Title Proteins Peptides Unique Peptides Spectra Identified Spectra View in Reactome
1 31118 HLA-B40-peptidome 1821 14368 2246 197847 13689