INCENP

Inner centromere protein is a protein that in humans is encoded by the INCENP gene. It is a regulatory protein in the chromosome passenger complex (CPC). It is involved in regulation of the catalytic proteins Aurora B and Aurora C. It acts in association with two other proteins - Survivin and Borealin. These proteins form a tight three-helical bundle. The N-terminal domain of INCENP is the domain involved in formation of this three-helical bundle while its C-terminal domain is responsible for the interaction with Aurora B.

In mammalian cells, two broad groups of centromere-interacting proteins have been described: constitutively binding centromere proteins and 'passenger' (or transiently interacting) proteins. The constitutive proteins include CENPA (centromere protein A), CENPB, CENPC1, and CENPD.

The term 'passenger proteins' encompasses a broad collection of proteins that localize to the centromere during specific stages of the cell cycle. These include CENPE; MCAK; KID; cytoplasmic dynein (e.g., DYNC1H1); CliPs (e.g. CLIP1); and CENPF/mitosin (CENPF). The inner centromere proteins (INCENPs), the initial members of the passenger protein group, display a broad localization along chromosomes in the early stages of mitosis but gradually become concentrated at centromeres as the cell cycle progresses into mid-metaphase. During telophase, the proteins are located within the midbody in the intercellular bridge, where they are discarded after cytokinesis.

Interactions
INCENP has been shown to interact with H2AFZ, Survivin and CDCA8. The ARK binding region has been found to be necessary and sufficient for binding to aurora-related kinase. This interaction has been implicated in the coordination of chromosome segregation with cell division in yeast.