Ki-67
Ki-67 (marker of proliferation Ki-67, encoded by MKI67 and also known as MIB-1 or PPP1R105) is a large nuclear protein that coats the surface of mitotic chromosomes. It disperses chromosomes in early mitosis and helps cluster them in late mitosis. Browse Assay Genie's current range of Ki-67 research reagents below, or read on for the biology behind the target.
Ki-67 associates with the surface of mitotic chromosomes and acts as a chromosome repellent in early mitosis and a chromosome attractant in late mitosis. After nuclear envelope disassembly it keeps individual chromosomes dispersed in the cytoplasm. In early mitosis it relocalises from nucleoli to the chromosome surface, where it forms extended brush structures covering a substantial fraction of that surface.
The Ki-67 brush has a high net electrical charge and acts as a surfactant. It forms a steric and electrostatic barrier that stops chromosomes collapsing into a single chromatin mass and allows independent chromosome motility. In anaphase the brush collapses and Ki-67 switches to a chromosome attractant, promoting chromosome clustering and helping exclude large cytoplasmic particles from the future nuclear space. Dephosphorylation during mitotic exit, together with exposure of a conserved basic patch, induces RNA-dependent formation of a liquid-like condensed phase on the chromosome surface. Ki-67 binds premature ribosomal RNAs during anaphase, promoting liquid-liquid phase separation, and binds DNA with a preference for supercoiled and AT-rich DNA. It does not contribute to the internal structure of mitotic chromosomes, and its role in chromatin organisation may be indirect.
The MKI67 gene is named for the original antigen identified by monoclonal antibody Ki-67, and HGNC places it among the protein phosphatase 1 regulatory subunits. NCBI Gene lists RNA binding and molecular condensate scaffold activity, with involvement in chromosome segregation and regulation of mitotic nuclear division. Ki-67 is implicated in Crohn's disease, colorectal cancer, graft-versus-host disease and HIV infection, and is a biomarker in conditions including Barrett's esophagus, interstitial cystitis, and lung and gastrointestinal cancers. The mouse ortholog is Mki67.
Ki-67 keeps mitotic chromosomes dispersed and then clusters them in anaphase, making it a focus for studies of chromosome segregation.
Dephosphorylation and RNA binding drive a liquid-like condensed phase on the chromosome surface, linking Ki-67 to molecular condensate studies.
Ki-67 is described as a biomarker in lung, gastrointestinal and endocrine gland cancers, and is implicated in colorectal cancer.
Ki-67 is implicated in Crohn's disease and graft-versus-host disease, and is a biomarker in Barrett's esophagus and interstitial cystitis.
Ki-67 coats mitotic chromosomes. In early mitosis its charged brush acts as a surfactant that keeps chromosomes apart, and in anaphase it switches to a chromosome attractant that promotes clustering. It also binds RNA and DNA, and supports liquid-like condensate formation on the chromosome surface.
The gene symbol is MKI67, and the protein is listed in UniProt as proliferation marker protein Ki-67. Aliases include MIB-1 and PPP1R105. The previous HGNC name was antigen identified by monoclonal antibody Ki-67, which reflects how the protein was first recognised.
A mouse ortholog, Mki67, is recorded. In humans, Ki-67 is implicated in Crohn's disease, colorectal cancer and graft-versus-host disease, and is a biomarker in lung and gastrointestinal cancers. Check the datasheet of any product for its validated reactivity.
Other proliferation markers, mitotic regulators and phosphatase-pathway proteins with products at Assay Genie.
Gene and protein annotations from HGNC, NCBI Gene and UniProt P46013; product specifications from Assay Genie datasheets.