Members of this family of Yersinia pseudo-tuberculosis mitogens adopt a sandwich structure consisting of nine strands in two beta sheets, in a jelly-roll topology. As with other super-antigens, they are able to excessively activate T cells by binding to the T cell receptor [1].

1: Crystal and solution structures of a superantigen from Yersinia pseudotuberculosis reveal a jelly-roll fold. Donadini R, Liew CW, Kwan AH, Mackay JP, Fields BA; Structure. 2004;12:145-156. PMID:14725774