This entry represents a short repeat found near the C-terminus of some RTX toxins such as Swiss:Q9KS12 [1]. AlphaFold models suggest this repeat forms a beta solenoid structure. These repeats contain a GXGXD motif in each repeat which is similar to that found in the RTX calcium-binding nonapeptide repeat Pfam:PF00353. This suggests that these repeats may also be needed for translocation via the type I secretion system [1].

1: MARTX, multifunctional autoprocessing repeats-in-toxin toxins. Satchell KJ; Infect Immun. 2007;75:5079-5084. PMID:17646359

2: Calcium-Driven Folding of RTX Domain beta-Rolls Ratchets Translocation of RTX Proteins through Type I Secretion Ducts. Bumba L, Masin J, Macek P, Wald T, Motlova L, Bibova I, Klimova N, Bednarova L, Veverka V, Kachala M, Svergun DI, Barinka C, Sebo P; Mol Cell. 2016;62:47-62. PMID:27058787