cell cycle

Ki-67/MKI67 is an antigen which is expressed during G1, S, G2, and M phases of the cell cycle (mitotically active cells), but not during G0 phase (resting cells). It is a large protein with expected molecular weight of about 395 kDa, and it has a very complex localization pattern within the nucleus, one which changes during cell cycle progression. During interphase, Ki-67 antigen can be exclusively detected in the nucleus, whereas in mitotic phase, most of Ki67 pool gets relocated to the chromosomal surface.

PCNA is a nuclear protein essential for DNA replication as well as DNA excision and mismatch repair pathways. It coordinates the recruitment and association of needed components during both of these processes, both of which are essential for cell cycle regulation and cell response to stress.  Through the symmetric association of three identical monomers, PCNA forms a toroidal, ring-shaped structure that encircles DNA. This serves as the scaffold upon which polymerases and other proteins dock and associate.

Nuclear Mitotic Apparatus protein (NuMA) is a cell cycle-related protein that acts as an organizer of the mitotic spindle during mitosis. It may be involved in coordinating the alignment of the mitotic spindle to the cellular polarity axis, which is a prerequisite for asymmetric cell division. NuMA is also a prominent component of interphase cell nuclear matrix; however its role during interphase is largely unknown.

Bromodeoxyuridine (BrdU) variously abbreviated as BrdU, BudR, and BrdUrd, is a synthetic thymidine analog that gets incorporated into the DNA of dividing cells during the S-phase of the cell cycle and has a long history of heavy use in molecular and cytokinetic studies (1).

RAD51 is a recombinase protein encoded by RAD51 gene in humans. Human RAD51 family members are highly similar to bacterial RecA and yeast Rad51, both biochemically and structurally. It is a 339-amino acid protein that plays an important role in homologous recombination (HR) of DNA during double-strand break (DSB) repair.

A-kinase anchor proteins (AKAPs), such as AKAP95/AKAP8, are scaffold proteins that contain a binding domain for the RI/RII subunit of protein kinase A (PKA). AKAPs orchestrate and synchronize cellular events by tethering the cAMP-dependent PKA and other signaling enzymes to organelles and membranes. This gene encodes a nuclear A-kinase anchor protein that binds to the RII alpha subunit of PKA and may play a role in chromosome condensation during mitosis (1).

NuMA, the major protein of the "Nucleus and Mitotic Apparatus", is a structural protein in vertebrates involved in cell cycle regulation. It localizes to the nucleus during interphase, and accumulates at the spindle poles during mitosis and NuMA has been implicated in the formation of the mitotic spindle, in particular in focusing the spindle poles (1).

Jumonji domain-containing protein 3 (JMJD3), identified as H3K27me3 demethylase, controls the expression of key regulators and markers of neurogenesis, and is required for commitment to the neural lineage. Nevertheless, the precise molecular targets of JMJD3 remain largely uncharacterized. The regulation of JMJD3 appears to be highly gene- and context- specific, suggesting interplay with specific molecules to promote fine-tuning more than the on/off alternation of methylation status.

Proliferating Cell Nuclear Antigen (PCNA), also known as the polymerase delta auxiliary protein, is a nuclear protein essential for DNA replication as well as DNA excision and mismatch repair pathways. It has a large role in cell cycle regulation and response of cells to stress.

BrdU (5-bromo-2-deoxyuridine) is a thymidine analogue which is incorporated into the cells of DNA synthetic phase. Replicating cells undergo DNA synthesis in a highly regulated, S-phase of the cell cycle. The regulation of cell proliferation is central to tissue morphogenesis during the development of multicellular organisms. Furthermore, loss of control of cell proliferation underlies the pathology of diseases like cancer.