This family describes the C-terminal region of various bacterial haemolysins and leukotoxins, which belong to the RTX family of toxins. These are produced by various Gram negative bacteria, such as E. coli (Swiss:P09983) and Actinobacillus pleuropneumoniae (Swiss:P15377). RTX toxins may interact with lipopolysaccharide (LPS) to functionally impair and eventually kill leukocytes [1]. This region is found in association with the RTX N-terminal domain (Pfam:PF02382) and multiple hemolysin-type calcium-binding repeats (Pfam:PF00353).

1: Biological effects of RTX toxins: the possible role of lipopolysaccharide. Czuprynski CJ, Welch RA; Trends Microbiol 1995;3:480-483. PMID:8800842