AMP is an adenosine A1 receptor agonist

Area of Science:

• Biochemistry
• Pharmacology
• Cell Biology

Background:

• The existence of receptors for adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine is well-established.
• However, whether adenosine 5 '-monophosphate (AMP) acts on specific receptors remained largely unexplored.

Purpose of the Study:

• To investigate the potential direct activation of purinergic receptors by AMP.
• To elucidate the mechanism by which AMP interacts with adenosine receptors.

Main Methods:

• Development and utilization of a novel cell-based assay for real-time visualization of adenosine receptor activation.
• Employing cAMP accumulation assays and site-directed mutagenesis of the adenosine A(1) receptor (A(1)R) ligand binding pocket.
• Testing the effects of AMP and its analog deoxyadenosine 5 '-monophosphonate (ACP) on receptor activation.

Main Results:

• AMP and ACP directly activated the adenosine A(1) receptor (A(1)R).
• AMP's activation of the adenosine A(2B) receptor (A(2B)R) was dependent on hydrolysis to adenosine by ecto-5 '-nucleotidase (NT5E) or prostatic acid phosphatase (PAP).
• Mutagenesis studies identified specific residues in the A(1)R binding pocket crucial for AMP recognition.

Conclusions:

• Adenosine 5 '-monophosphate (AMP) functions as a direct, full agonist of the adenosine A(1) receptor (A(1)R).
• These findings indicate that AMP may exert direct physiological effects independent of its conversion to adenosine.