MAP/Microtubule Affinity Regulating Kinase 2 (MARK2)

Association of CagA inhibited PAR1b (MARK2) kinase activity and prevented atypical protein kinase C-mediated PAR1 phosphorylation, which dissociates PAR1 from the membrane, collectively causing junctional and polarity defects. Because of the multimeric nature of PAR1, PAR1 also promoted CagA multimerization, which stabilized the CagA-SHP2 (PTPN11) interaction. Furthermore, induction of the hummingbird phenotype by CagA-activated SHP2 required simultaneous inhibition of PAR1 kinase activity by CagA. The largest cDNA encodes a 745-amino acid protein with conserved kinase and ELKL-box domains. Northern blot analysis detected expression of a major EMK1 band of approximately 4.4 kb at high levels in heart, brain, placenta, skeletal muscle, and pancreas, and at lower levels in lung, liver, and kidney.