Protein tyrosine phosphatase beta, a receptor for Helicobacter pylori vacA toxin.

Helicobacter pylori is the leading bacterial cause of food-borne illness worldwide and plays a major role in the development of chronic gastritis, peptic ulcer, and gastric cancer. Strains isolated from patients contain the cagA gene (cytotoxin-associated gene A) and produce the vacuolating cytotoxin VacA. VacA binding to specific high-affinity cell surface receptors was shown by using indirect immunofluorescence and flow cytometry; high-affinity toxin binding was necessary for cell intoxication. A 250-kDa receptor protein tyrosine phosphatase (RPTP) beta served as a receptor for VacA on AZ-521 cells. The overexpression of RPTP beta conferred VacA sensitivity on BHK-21 cells transfected with the RPTP beta cDNA, consistent with RPTP gamma acting as a receptor for VacA. Increased binding of acid- or alkali-activated VacA to RPTP gamma may alter its activity and possibly accelerate or inhibit dephosphorylation of tyrosine on cytosolic proteins. Understanding the pathological responses of wild type and RPTP gamma-deficient animal models may well provide valuable information regarding the mechanism of VacA toxicity.