This family of proteins is found in bacteria. Family members are approximately 40 amino acids in length. There is a conserved GKAW sequence motif. There is a single completely conserved residue G that may be functionally important. Family members include the Bacillus subtilis cell-division inhibitor, MciZ (mother cell inhibitor of FtsZ) which blocks the assembly of FtsZ. FtsZ (filamentation temperature-sensitive Z) is the bacterial homolog of tubulin. Crystal structure reveals that MciZ binds to the C-terminal polymerization interface of FtsZ, the equivalent of the minus end of tubulin, causing shortening of protofilaments and blocking the assembly of higher-order FtsZ structures. Hence, MciZ provides a capping-based regulatory mechanism for FtsZ [1].

1: FtsZ filament capping by MciZ, a developmental regulator of bacterial division. Bisson-Filho AW, Discola KF, Castellen P, Blasios V, Martins A, Sforca ML, Garcia W, Zeri AC, Erickson HP, Dessen A, Gueiros-Filho FJ; Proc Natl Acad Sci U S A. 2015;112:E2130-E2138. PMID:25848052