Tyrosine 288 in the extracellular domain of the human P2X7 receptor is critical for receptor function revealed by structural modeling and site-directed mutagenesis.

Abstract

The P2X7 receptor (P2X7R) is a calcium-permeable cation channel activated by high concentrations of extracellular ATP. It plays a role in vital physiological processes, particularly in innate immunity, and is dysregulated in pathological conditions such as inflammatory diseases, neurodegenerative diseases, mood disorders, and cancers. Structural modeling of the human P2X7R (hP2X7R) based on the recently available structures of the rat P2X7 receptor (rP2XR) in conjunction with molecular docking predicts the orientation of tyrosine at position 288 (Y288) in the extracellular domain to face ATP. In this short communication, we combined site-directed mutagenesis and whole-cell patch-clamp recording to investigate the role of this residue in the hP2X7R function. Mutation of this extracellular residue to amino acids with different properties massively impaired current responses to both ATP and BzATP, suggesting that Y288 is important for normal receptor function. Such a finding facilitates development of an in-depth understanding of the molecular basis of hP2X7R structure-function relationships.