During the division cyle of E. coli, at the end of the daughter chromosome segregation process, FtsZ proteins assembles into the Z ring on the inner face of the cytoplasmic membrane at the cell centre, marking the future division site. The Z ring then recruits at least ten membrane-associated proteins to assemble the cell-division protein machinery. This machinery synthesizes the division septum, which consists of cell-wall material between the two daughter celles, with the Z ring at the leading edge of membrane invagination. Contraction of the Z ring and constriction of the outer membrane follow.
The Z-ring before contraction containing about 2000 FtsZ proteins (800 nm diameter) is superimposed with the whole machinery close to the septum closure. FtsK monomers are attached to the Z-ring through a 200 nm linker not represented.
See for more information :
W. Margolin : FtsZ and the division of prokaryotic cells and organelles. Nature Reviews Molecular Cell Biology 6, 862-871 (November 2005).
S. Bigot, V. Sivanathan, C. Possoz F.-X. Barre and F. Cornet : FtsK, a literate chromosome segregation machine. Molecular Microbiology (2007) 64(6), 1434–1441