InterPro domain: IPR003008

This entry represents a GTPase domain found in all tubulin chains, such as tubulin alpha, beta and gamma chains, plant ARC3 and prokaryotic FtsZ and CetZ proteins [ 1 , 2 ]. These proteins are involved in polymer formation. Tubulin is the major component of microtubules, while FtsZ (homologue of eukaryotic tubulin) is the polymer-forming protein of bacterial cell division, it is part of a ring in the middle of the dividing cell that is required for constriction of cell membrane and cell envelope to yield two daughter cells [ 3 , 4 ]. FtsZ can polymerise into tubes, sheets, and rings in vitro and is ubiquitous in bacteria and archaea. CetZ co-exists with FtsZ in many archaea. Cetz does not affect cell division, instead, it is involved in cell shape control [ 5 ]. Arabidopsis chloroplast protein ARC3 (At1g75010) is a Z-ring accessory protein involved in the initiation of plastid division and division site placement [ 6 , 7 ].

1. Tubulin and FtsZ form a distinct family of GTPases. Nat. Struct. Biol. 5, 451-8
2. The role of dynamic instability in microtubule organization. Front Plant Sci
3. An essential cell division gene of Drosophila, absent from Saccharomyces, encodes an unusual protein with tubulin-like and myosin-like peptide motifs. Proc. Natl. Acad. Sci. U.S.A. 94, 5189-94
4. Crystal structure of the bacterial cell-division protein FtsZ. Nature 391, 203-6
5. CetZ tubulin-like proteins control archaeal cell shape. Nature 45, 960-7
6. ARC3, a chloroplast division factor, is a chimera of prokaryotic FtsZ and part of eukaryotic phosphatidylinositol-4-phosphate 5-kinase. Plant Cell Physiol. 84, 1324-35
7. Effects of arc3, arc5 and arc6 mutations on plastid morphology and stromule formation in green and nongreen tissues of Arabidopsis thaliana. Photochem. Photobiol. 5, 511