This repeat is found in the CagY proteins - part of the CAG pathogenicity island - and involved in delivery of the protein CagA into host cells ([1]). It forms part of a surface needle structure, and this repeat may form an alpha-helical rod structure ([1]). A conserved -DC- and -EC- can be seen in regularly spaced in the alignment.

1: A novel sheathed surface organelle of the Helicobacter pylori cag type IV secretion system. Rohde M, Puls J, Buhrdorf R, Fischer W, Haas R; Mol Microbiol 2003;49:219-234. PMID:12823823

2: The highly repetitive region of the Helicobacter pylori CagY protein comprises tandem arrays of an alpha-helical repeat module. Delahay RM, Balkwill GD, Bunting KA, Edwards W, Atherton JC, Searle MS; J Mol Biol. 2008;377:956-971. PMID:18295231