MKI67
Description
The MKI67 (marker of proliferation Ki-67) is a protein-coding gene located on chromosome 10.
MKI67, also known as Ki-67, is a protein encoded by the MKI67 gene. It is a nuclear protein associated with cellular proliferation and ribosomal RNA transcription. Inactivation of MKI67 inhibits ribosomal RNA synthesis, but does not significantly affect cell proliferation in vivo. MKI67 is a cellular marker for proliferation and is strictly associated with cell proliferation. During interphase, MKI67 can be exclusively detected within the cell nucleus, whereas in mitosis most of the protein is relocated to the surface of the chromosomes. It is present during all active phases of the cell cycle (G1, S, G2, and mitosis), but is absent in resting cells (G0). Cellular content of MKI67 protein markedly increases during cell progression through S phase of the cell cycle. In breast cancer, Ki67 identifies a high proliferative subset of patients with ER-positive breast cancer who derive greater benefit from adjuvant chemotherapy. MKI67 is an excellent marker to determine the growth fraction of a given cell population.
MKI67 is required to maintain individual mitotic chromosomes dispersed in the cytoplasm following nuclear envelope disassembly. It associates with the surface of the mitotic chromosome, the perichromosomal layer, and covers a substantial fraction of the chromosome surface. MKI67 prevents chromosomes from collapsing into a single chromatin mass by forming a steric and electrostatic charge barrier. The protein has a high net electrical charge and acts as a surfactant, dispersing chromosomes and enabling independent chromosome motility. MKI67 binds DNA, with a preference for supercoiled DNA and AT-rich DNA. It does not contribute to the internal structure of mitotic chromosomes. MKI67 may play a role in chromatin organization, but it is unclear whether this is a direct role or an indirect consequence of its function in maintaining mitotic chromosomes dispersed.
MKI67 is also known as KIA, MIB-, MIB-1, PPP1R105.
