Dysregulation of the tight junction by H. pylori. H. pylori preferentially bind in close proximity to the tight junction and disrupt gastric barrier function, cell adhesion, and cell polarity which culminates in an invasive phenotype. Tight junctions are composed of the integral membrane proteins occludin, claudins, and junctional adhesion molecule (JAM)-A, as well as zonula occludens-1 (ZO-1). Tight junction function is disrupted by urease activity and phosphorylation of myosin light chain (MLC) by myosin light chain kinase (MLCK) or Rho kinase (ROCK). Translocated CagA interacts with partitioning-defective 1 (PAR1) to inhibit phosphorylation by blocking PAR1 kinase activity and disrupts the tight junction. VacA also increases tight junction permeability.