Secreted protein specifically required to prevent invasion of Gram-negative bacteria in the inner mucus layer of the colon epithelium, a portion of the large intestine which is free of commensal microbiota. Prevents invasion of flagellated microbiota by binding to the flagellum of bacteria, such as P.mirabilis, thereby inhibiting bacterial motility in the intestinal lumen. Segregation of intestinal bacteria and epithelial cells in the colon is required to preserve intestinal homeostasis. . This is the function of ENSG00000259823 (LYPD8, LY6/PLAUR domain containing 8).