Mki67

Developmental stage

Accumulates during the late G1 stage in the nucleus and maximum expression is found during G2 phase and mitosis (PubMed:8834799). During male meiosis, present in nuclei of all stages from the spermatogonium through spermatocytes I and II up to the earliest spermatid stage (early round spermatids) and then fades out (PubMed:12355204). Not detected in later spermatid stages or sperm (PubMed:12355204). During female meiosis, present in prophase I oocytes of fetal ovaries, while it is absent in resting oocytes. Reappears in oocytes of growing follicles and is continuously present up to metaphase II (at protein level) (PubMed:12355204).

Function

Required to maintain individual mitotic chromosomes dispersed in the cytoplasm following nuclear envelope disassembly (PubMed:27362226). Associates with the surface of the mitotic chromosome, the perichromosomal layer, and covers a substantial fraction of the chromosome surface (PubMed:27362226). 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 (PubMed:27362226). Binds DNA, with a preference for supercoiled DNA and AT-rich DNA (By similarity). Does not contribute to the internal structure of mitotic chromosomes (PubMed:26949251). May play a role in chromatin organization (PubMed:26949251). It is however unclear whether it plays a direct role in chromatin organization or whether it is an indirect consequence of its function in maintaining mitotic chromosomes dispersed.

Post-translational modifications

Phosphorylated. Hyperphosphorylated in mitosis. Hyperphosphorylated form does not bind DNA.

Tissue Specificity

Mainly present in proliferating cells (at protein level).

Cellular localization

• Chromosome
• Nucleus
• Nucleus
• Nucleolus
• Associates with the surface of the mitotic chromosome, the perichromosomal layer, and covers a substantial fraction of the mitotic chromosome surface (PubMed:12355204, PubMed:8834799). Associates with satellite DNA in G1 phase (By similarity). Binds tightly to chromatin in interphase, chromatin-binding decreases in mitosis when it associates with the surface of the condensed chromosomes (By similarity). Predominantly localized in the G1 phase in the perinucleolar region, in the later phases it is also detected throughout the nuclear interior, being predominantly localized in the nuclear matrix (By similarity).

Alternative names

Proliferation marker protein Ki-67, Antigen identified by monoclonal antibody Ki-67 homolog, Antigen KI-67 homolog, Antigen Ki67 homolog, Mki67

Database links

swissprot:E9PVX6 swissprot:Q61769 entrezGene:17345

Other research areas

• Neuroscience
• Oncology