Pannexin2 (Panx2) is the largest of three members of the pannexin proteins. 
Pannexins are topologically related to connexins and innexins, but serve 
different functional roles than forming gap junctions. We previously showed that 
pannexins form oligomeric channels but unlike connexins and innexins, they form 
only single membrane channels. High levels of Panx2 mRNA and protein in the 
Central Nervous System (CNS) have been documented. Whereas Pannexin1 (Panx1) is 
fairly ubiquitous and Pannexin3 (Panx3) is found in skin and connective tissue, 
both are fully glycosylated, traffic to the plasma membrane and have functions 
correlated with extracellular ATP release. Here, we describe trafficking and 
subcellular localizations of exogenous Panx2 and Panx1 protein expression in 
MDCK, HeLa, and HEK 293T cells as well as endogenous Panx1 and Panx2 patterns in 
the CNS. Panx2 was found in intracellular localizations, was partially 
N-glycosylated, and localizations were non-overlapping with Panx1. Confocal 
images of hippocampal sections immunolabeled for the astrocytic protein GFAP, 
Panx1 and Panx2 demonstrated that the two isoforms, Panx1 and Panx2, localized 
at different subcellular compartments in both astrocytes and neurons. Using 
recombinant fusions of Panx2 with appended genetic tags developed for correlated 
light and electron microscopy and then expressed in different cell lines, we 
determined that Panx2 is localized in the membrane of intracellular vesicles and 
not in the endoplasmic reticulum as initially indicated by calnexin 
colocalization experiments. Dual immunofluorescence imaging with protein markers 
for specific vesicle compartments showed that Panx2 vesicles are early endosomal 
in origin. In electron tomographic volumes, cross-sections of these vesicles 
displayed fine structural details and close proximity to actin filaments. Thus, 
pannexins expressed at different subcellular compartments likely exert distinct 
functional roles, particularly in the nervous system.