ribonucleoside-diphosphate reductase complex

Definition

Target type: cellularcomponent

An enzyme complex composed of 2-4 or more subunits, which usually contains nonheme iron and requires ATP for catalysis. Catalyzes the formation of 2'-deoxyribonucleoside diphosphate from ribonucleoside diphosphate, using either thioredoxin disulfide or glutaredoxin disulfide as an acceptor. [BRENDA:1.17.4.1]

The ribonucleoside-diphosphate reductase (RNR) complex is a crucial enzyme responsible for the conversion of ribonucleotides (ADP, CDP, GDP, UDP) to deoxyribonucleotides (dADP, dCDP, dGDP, dUDP), essential building blocks for DNA synthesis. It is a multi-subunit complex, with two major components: RNR1 (also known as R1 or RNR large subunit) and RNR2 (also known as R2 or RNR small subunit).

RNR1 contains the catalytic site and is responsible for the actual reduction reaction, while RNR2 serves as a radical generator. Both subunits are required for enzymatic activity.

The RNR1 subunit is responsible for:

* **Binding of the ribonucleotide substrate and the cofactor NADPH.**
* **Housing the catalytic site.**
* **Providing the tyrosine radical.**

The RNR2 subunit is responsible for:

* **Generating the essential tyrosyl radical for the reduction reaction.**
* **Transferring the radical to the RNR1 subunit.**
* **Binding to the RNR1 subunit through a complex mechanism that involves protein-protein interactions.**

The cellular component of the RNR complex is highly dynamic and can be found in various subcellular locations, depending on the cell type and stage of the cell cycle. However, in general, the RNR complex is primarily located in the **nucleus** during DNA replication.

Here's a summary of the key features of the RNR complex:

* **Location:** Primarily nuclear, but can be found in other cellular compartments like cytoplasm and mitochondria.
* **Structure:** Composed of two subunits, RNR1 and RNR2.
* **Function:** Catalyzes the reduction of ribonucleotides to deoxyribonucleotides, essential for DNA synthesis.
* **Regulation:** Regulated by various mechanisms, including protein-protein interactions, phosphorylation, and redox potential.

Overall, the RNR complex is a vital component of DNA replication, contributing to the synthesis of the genetic material necessary for cell division and organismal development.'
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Proteins (3)

Compounds (5)