G1 Cyclins
G1 Cyclins - Related Videos
10:54
Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations
0 Views •
Cited by 2 •
2012
Metaphase to anaphase transition is triggered through anaphase-promoting complex (APC/C)-dependent ubiquitination and subsequent destruction of cyclin B. Here, we established a system which, following pulse-chase labeling, allows monitoring cyclin B proteolysis in entire cell populations and facilitates the detection of interference by the mitotic checkpoint.
08:30
Visualizing Single-Stranded DNA Foci in the G1 Phase of the Cell Cycle
0 Views •
Cited by 2 •
2023
The following protocol presents the detection of single-stranded DNA foci in the G1 phase of the cell cycle utilizing cell cycle synchronization followed by RPA2 immunofluorescent staining.
12:26
Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
0 Views •
Cited by 10 •
2018
Cyclin-dependent kinase 1 (Cdk1) is activated in the G2 phase of the cell cycle and regulates many cellular pathways. Here, we present a protocol for an in vitro kinase assay with Cdk1, which allows the identification of Cdk1-specific phosphorylation sites for establishing cellular targets of this important kinase.
01:45
Positive Regulator Molecules
0 Views •
2019
To consistently produce healthy cells, the cell cycle—the process that generates daughter cells—must be precisely regulated. Internal regulatory checkpoints ensure that a cell’s size, energy reserves, and DNA quality and completeness are sufficient to advance through the cell cycle. At these checkpoints, positive and negative regulators promote or inhibit a cell’s continuation through the cell cycle. Positive regulators include two protein groups that allow cells to pass through regulatory...
01:23
Negative Regulator Molecules
0 Views •
2019
Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria. Three of the best-understood negative regulators are p53, p21, and retinoblastoma protein (Rb). The regulatory roles of each of these proteins were discovered after faulty copies were found in cells with uncontrolled replication (i.e., cancer). These...
FAQs
Mitogenic signals stimulate cyclin D association with CDK4/6, leading to phosphorylation of the retinoblastoma protein. This releases E2F transcription factors, which promote cyclin E production and subsequent CDK2 activation at the G1/S transition. The sequential relay links extracellular growth information to the decision to begin DNA replication rather than treating replication as an isolated event.
Retinoblastoma protein phosphorylation changes the regulatory relationship between the cell-cycle machinery and E2F transcription factors. Once phosphorylation releases E2F, transcriptional activity supports cyclin E production and progression toward the G1/S transition. This control point is important because it connects cyclin D-CDK4/6 activity with the gene-expression changes needed for continued cell-cycle advancement.
Cyclin D and cyclin E act sequentially rather than performing identical functions. Cyclin D partners with CDK4/6 to phosphorylate retinoblastoma protein, while the resulting E2F activity promotes cyclin E production. Cyclin E then supports CDK2 activation at the G1/S transition. Their order of action illustrates how cells build a stepwise commitment to DNA replication.
A useful conceptual workflow follows the sequence from mitogenic input to cyclin D-CDK4/6 activity, retinoblastoma protein phosphorylation, E2F release, cyclin E production, and CDK2 activation. Examining this order helps distinguish an upstream signaling response from the later G1/S transition. It also clarifies where regulatory failure may interrupt normal progression through the cell cycle.
G1 cyclins connect growth-promoting cues with cell-cycle entry, providing a molecular context for studying how cells coordinate proliferation with broader biological demands. In developmental biology, this connection helps frame growth and development, while in tissue maintenance it supports analysis of regulated proliferative activity. Their study therefore links cell-cycle control with processes that shape and preserve tissues.
Cancer relevance arises when controls governing proliferation fail, contributing to tumor progression. Studying the cyclin D, retinoblastoma protein, E2F, cyclin E, and CDK sequence helps identify how normal growth control becomes disrupted. The same pathway provides context for therapies targeting cyclin-dependent kinases, connecting molecular mechanism with research into treatment strategies for abnormal proliferation.