What are pRb and p53?
pRb and p53 are the two major tumor suppressors. Their inactivation is frequent when cancers develop and their reactivation is rationale of most cancer therapeutics. When pRb and p53 are genetically inactivated, cells irreparably lose the antitumor mechanisms afforded by them.
What are Rb and p53 proteins?
p53 and RB are at the heart of the two main tumour-suppressor pathways that control cellular responses to potentially oncogenic stimuli. Each pathway consists of several upstream regulators and downstream effectors. For simplicity, only four main components in each pathway are shown.
What property of p53 makes it a tumor suppressor?
The tumor suppressor p53 is a phosphoprotein barely detectable in the nucleus of normal cells. Upon cellular stress, particularly that induced by DNA damage, p53 can arrest cell cycle progression, thus allowing the DNA to be repaired; or it can lead to apoptosis.
How does p53 function as a tumor suppressor protein?
This protein acts as a tumor suppressor, which means that it regulates cell division by keeping cells from growing and dividing (proliferating) too fast or in an uncontrolled way. The p53 protein is located in the nucleus of cells throughout the body, where it attaches (binds) directly to DNA.
What does Rb protein do?
The Rb protein is a tumor suppressor, which plays a pivotal role in the negative control of the cell cycle and in tumor progression. It has been shown that Rb protein (pRb) is responsible for a major G1 checkpoint, blocking S-phase entry and cell growth.
Does p53 bind to RB?
RB does so through its ability to form a trimeric complex with p53 via binding to MDM2. The p53 in the trimeric complex was transcriptionally inactive but able to induce apoptosis.
Why are Rb and other proteins called tumor suppressors?
The RB1 gene provides instructions for making a protein called pRB. This protein acts as a tumor suppressor, which means that it regulates cell growth and keeps cells from dividing too fast or in an uncontrolled way.
What is a tumor suppressor protein?
A tumor suppressor gene directs the production of a protein that is part of the system that regulates cell division. The tumor suppressor protein plays a role in keeping cell division in check. When mutated, a tumor suppressor gene is unable to do its job, and as a result uncontrolled cell growth may occur.
What kind of protein is p53?
2 P53. P53 is a tumor suppressor protein that could be activated in response to hypoxia, DNA damage, and loss of normal cell contacts (Fridman and Lowe, 2003). MDM2 (or HDM2 in humans) is an oncoprotein that can inactivate P53 tumor suppressor. In fact, p53 and MDM2 protein are in a balanced situation in normal cell.
What does the Rb protein do?
What are tumor suppressor proteins?
Definition. Tumour-suppressor proteins act to alleviate the potential for cancer and tumour formation by modulating cell growth either through negative regulation of the cell cycle or by promoting apoptosis.