InterPro domain: IPR016098

Cyclase-associated proteins (CAPs) are highly conserved monomeric actin-binding proteins present in a wide range of organisms including yeast, fly, plants, and mammals. CAPs are multifunctional proteins that contain several structural domains. CAP is involved in species-specific signalling pathways [ 1 , 2 , 3 , 4 ]. Only yeast CAPs are involved in adenylate cyclase activation. The C-terminal domain of CAP proteins is responsible for G-actin-binding that regulates actin remodelling in response to cellular signals and is required for normal cellular morphology, cell division, growth and locomotion in eukaryotes.

In Escherichia coli, three Min proteins (MinC, MinD and MinE) negatively regulate FtsZ assembly at the cell poles in order to ensure the Z-ring only assembles at cell midpoint. MinC inhibits formation of the Z-ring by preventing FtsZ assembly. MinD binds to MinC near the cell poles, sequestering MinC away from the cell midpoint so the Z-ring can form there. MinC is an oligomer, probably a dimer, that consists of two domains: the N-terminal domain is responsible for FtsZ inhibition, while the C-terminal domain is responsible for binding to MinD and to a component of the division septum [ 5 , 6 ].

This entry represents a structural domain found at the C-terminal of CAP proteins as well as MinC. This domain has a superhelical structure, where the superhelix turns are made of either two (CAP) or three (MinC) beta-strands each.

1. Cyclase-associated proteins: CAPacity for linking signal transduction and actin polymerization. FASEB J. 16, 487-99
2. Arabidopsis CAP1 - a key regulator of actin organisation and development. J. Cell. Sci. 120, 2609-18
3. Mammalian homolog of the yeast cyclase associated protein, CAP/Srv2p, regulates actin filament assembly. Cell Motil. Cytoskeleton 45, 106-20
4. Crystallization of cyclase-associated protein from Dictyostelium discoideum. Acta Crystallogr. D Biol. Crystallogr. 58, 1858-61
5. Analysis of MinC reveals two independent domains involved in interaction with MinD and FtsZ. J. Bacteriol. 182, 3965-71
6. The C-terminal domain of MinC inhibits assembly of the Z ring in Escherichia coli. J. Bacteriol. 189, 236-43