Role of an Aromatic-Aromatic Interaction in the Assembly and Trafficking of the Zebrafish Panx1a Membrane Channel

Pannexin 1 (Panx1) is a ubiquitously expressed hexameric integral membrane protein known to function as an adenosine triphosphate (ATP) release channel. Panx1 proteins exist in unglycosylated core form (Gly0). They undergo critical post-translational modifications forming the high mannose glycosylation state (Gly1) in the endoplasmic reticulum (ER) and the complex glycosylation state (Gly2) in the Golgi apparatus. The regulation of transition from the ER to the cell membrane is not fully understood. Using site-specific mutagenesis, dye uptake assays, and interaction testing, we identified two conserved aromatic residues, Trp123 and Tyr205, in the transmembrane domains 2 and 3 of the zebrafish panx1a protein. Results suggest that both residues primarily govern the assembly of panx1a subunits into channels, with mutant proteins failing to interact. The results provide insight into a mechanism enabling regulation of Panx1 oligomerization, glycosylation, and trafficking.