Retinoblastoma protein (Rb)

Definition

Retinoblastoma protein (Rb) is a tumor suppressor protein that plays a crucial role in regulating the cell cycle. It prevents excessive cell growth by inhibiting cell cycle progression until a cell is ready to divide.

5 Must Know Facts For Your Next Test

1. Rb controls the transition from the G1 phase to the S phase of the cell cycle.
2. When Rb is phosphorylated, it becomes inactivated and allows for cell cycle progression.
3. Mutations in the Rb gene can lead to uncontrolled cell division and are associated with various cancers, including retinoblastoma.
4. Rb interacts with E2F transcription factors to regulate gene expression necessary for DNA replication.
5. Loss of Rb function results in unregulated activity of E2F, leading to unchecked cellular proliferation.

Review Questions

• What role does Rb play in the regulation of the cell cycle?
• How does phosphorylation affect the activity of Rb?
• Which types of cancer are commonly associated with mutations in the Rb gene?

Related terms

Cyclins:

Proteins that regulate different phases of the cell cycle by activating cyclin-dependent kinases (CDKs).

E2F Transcription Factors: A group of genes that code for a family of transcription factors involved in controlling the cell cycle and action of tumor suppressor proteins like Rb.

p53 Protein: Another tumor suppressor protein that regulates the cell cycle and helps prevent cancer formation by inducing apoptosis or halting cell division when DNA damage is detected.