Characterization of N- and C-termini of HER2 protein by mass spectrometry-based sequencing: Observation of two types of N-terminal sequence

•We analyzed N- and C-terminal sequences of HER2 by mass spectrometry-based methods.•Two types of N-terminal sequence were observed. One of them was already reported, but the other was not.•The C-terminal sequence was identical to the sequence already reported.

N- and C-terminal amino acid sequences of human epidermal growth factor receptor-2 (HER2), purified from breast cancer cell lines (SK-BR-3 and BT-474), were analyzed at the protein level using mass spectrometry. Two N-terminal peptides and one C-terminal peptide were obtained. Their MALDI-PSD analyses indicated that one of the N-terminal sequences and the C-terminal sequence were identical to those found in UniProtKB/Swiss-Prot. However, the other N-terminal sequence was not in the database and was considered as a novel variant. This variant may result from the cleavage at a potential alternative site for cleavage of the signal peptide.

Graphical abstractThis mass spectrum indicates that two types of N-terminal amino acid sequence were obtained for HER2 protein extracted from a cell line of BT-474. Ccam indicates S-carbamidomethylcysteine residue.Figure optionsDownload full-size imageDownload high-quality image (134 K)Download as PowerPoint slide