3'-phosphoadenosine 5'-phosphosulfate metabolic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways involving 3'-phosphoadenosine 5'-phosphosulfate, a naturally occurring mixed anhydride. It is an intermediate in the formation of a variety of sulfo compounds in biological systems. [ISBN:0198506732]

3'-Phosphoadenosine 5'-phosphosulfate (PAPS) is a key intermediate in the biosynthesis of sulfated molecules, such as glycosaminoglycans, steroids, and proteins. The PAPS metabolic process encompasses a series of enzymatic reactions that generate and utilize PAPS as a sulfur donor.

**1. Sulfate Activation:**
The process begins with the activation of inorganic sulfate (SO42-) to PAPS. This activation is catalyzed by the enzyme ATP sulfurylase, which uses ATP to convert sulfate to adenosine 5'-phosphosulfate (APS). Subsequently, APS kinase further phosphorylates APS, using another molecule of ATP, to produce PAPS.

**2. PAPS as a Sulfur Donor:**
PAPS serves as the universal sulfur donor in sulfation reactions. It is utilized by a variety of sulfotransferases, which are enzymes that catalyze the transfer of the sulfate group from PAPS to a wide range of acceptor molecules. These acceptor molecules include:

* **Glycosaminoglycans:** PAPS is involved in the sulfation of glycosaminoglycans, such as chondroitin sulfate, heparan sulfate, and dermatan sulfate. These sulfated glycosaminoglycans play critical roles in structural support, cell signaling, and tissue development.
* **Steroids:** PAPS is used in the sulfation of steroid hormones, such as estrogen and testosterone. Sulfation of steroids can modulate their activity and influence their metabolism.
* **Proteins:** PAPS is involved in the sulfation of proteins, a post-translational modification that can alter protein function, stability, and localization. Sulfated proteins are involved in diverse biological processes, including signal transduction, cell adhesion, and immune responses.

**3. PAPS Metabolism Regulation:**
The PAPS metabolic process is tightly regulated to maintain appropriate levels of sulfated molecules. The activity of enzymes involved in PAPS biosynthesis, such as ATP sulfurylase and APS kinase, can be modulated by factors such as substrate availability, cellular conditions, and hormonal signaling.

In summary, the 3'-phosphoadenosine 5'-phosphosulfate (PAPS) metabolic process is a crucial pathway for the biosynthesis of a wide range of sulfated molecules that play essential roles in various biological processes.'
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Proteins (4)

Compounds (18)