The proximal C-terminal domain of P2X subunits contains a semi-conserved PIP_n-binding motif.

<p>A) Sequence alignment of rat P2X C-termini proximal to the TM2 domain showing the two polybasic clusters (shaded area, 1 and 2). The left column summarizes, for each subunit, the presence (+) or absence (−) of binding of the GST-fusion C-terminal domain to PIP_n in PIP strip assays. The second column shows the presence (+) or absence (−) of modulation by PIP_n in functional assays. Basic residues are shown in red and acidic residues in blue. B) Sequences showing residues that were reported (here or previously) to be involved in PIP_n regulation. Basic residues in red, acidic residues in blue and an uncharged serine in green. C) Schematic representation of the topology of a P2X subunit showing binding of two positively charged amino acid clusters to membrane-bound PIP_n.