Purification of Her-2 extracellular domain and identification of its cleavage site

Area of Science:

• Molecular Biology
• Biochemistry
• Oncology

Background:

• The Epidermal Growth Factor Receptor (EGFR) family, including Her-2/neu/c-erbB-2, are tyrosine kinase receptors (TKRs).
• These receptors are vital in embryonic and postnatal development and implicated in tumor progression.
• Her-2 can be processed into a soluble extracellular domain (ECD) and a membrane-bound fragment.

Purpose of the Study:

• To identify the precise cleavage sites responsible for generating the soluble extracellular domain (ECD) of the Her-2 receptor.
• To analyze the biochemical characteristics of Her-2 ECD generated from a breast cancer cell line.

Main Methods:

• Immunopurification of Her-2 ECD from the SKBR3 breast cancer cell line.
• Analysis using matrix-assisted laser desorption ionization (MALDI) mass spectrometry.
• Carboxyl-terminal amino acid sequencing.

Main Results:

• Identified a primary cleavage site within the juxtamembrane region as PAEQRASP (11 amino acid residues).
• A minor cleavage site, PA EQRASP, was also detected.
• These cleavage sites are located within a conserved P/GX(5-7)P/G motif common to the EGFR family.

Conclusions:

• The study precisely mapped the cleavage sites generating soluble Her-2 ECD.
• These findings provide insights into the post-translational modification of Her-2.
• Understanding these cleavage mechanisms is important for Her-2 targeted cancer therapies.