Adenylyl cyclase

Enzyme that catalyzes the conversion of ATP to cyclic AMP

Adenylyl cyclase is an important enzyme in the cell signaling pathways of many organisms. It catalyzes the conversion of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP) and pyrophosphate. cAMP is a crucial second messenger involved in transmitting signals from extracellular stimuli to intracellular responses.

Structure

Adenylyl cyclase is a membrane-bound enzyme that typically consists of two transmembrane domains, each containing six membrane-spanning helices, and two cytoplasmic domains that form the catalytic core. The catalytic domains are responsible for the conversion of ATP to cAMP.

Function

Adenylyl cyclase plays a key role in the G protein-coupled receptor (GPCR) signaling pathway. When a ligand binds to a GPCR, it activates a G protein, which in turn activates adenylyl cyclase. The activated adenylyl cyclase then converts ATP to cAMP, which acts as a second messenger to activate downstream signaling pathways, such as the protein kinase A (PKA) pathway.

Regulation

The activity of adenylyl cyclase is regulated by various factors, including G proteins, calcium ions, and phosphorylation. Different isoforms of adenylyl cyclase can be activated or inhibited by different G proteins, allowing for fine-tuned regulation of cAMP production in response to different signals.

Isoforms

There are multiple isoforms of adenylyl cyclase, each with distinct regulatory properties and tissue distribution. These isoforms allow for specific responses to different signals in various tissues.

Clinical significance

Dysregulation of adenylyl cyclase activity can lead to various diseases, including heart failure, depression, and certain types of cancer. Understanding the role of adenylyl cyclase in these conditions can help in the development of targeted therapies.

Related pages

• Cyclic adenosine monophosphate
• G protein-coupled receptor
• Protein kinase A
• Signal transduction

Gallery

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  Structure of adenylyl cyclase
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  Adenylate kinase
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  Adenylyl cyclase
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  Beta adrenergic receptor kinase