In the retina, chemical and electrical synapses couple neurons into functional 
networks. New candidates encoding for electrical synapse proteins have recently 
emerged. In the present study, we determined the localization of the candidate 
protein pannexin1 (zfPanx1) in the zebrafish retina and studied the functional 
properties of zfPanx1 exogenously expressed in Neuroblastoma 2a (N2a) cells. 
zfPanx1 was identified on the surface of horizontal cell dendrites invaginating 
deeply into the cone pedicle near the glutamate release sites of the cones, 
providing in vivo evidence for hemichannel formation at that location. This 
strategic position of zfPanx1 in the photoreceptor synapse could potentially 
allow modulation of cone output. Using whole cell voltage clamp and excised 
patch recordings of transfected N2a cells, we demonstrated that zfPanx1 forms 
voltage-activated hemichannels with a large unitary conductance in vitro. These 
channels can open at physiological membrane potentials. Functional channels were 
not formed following mutation of a single amino acid within a conserved protein 
motif recently shown to be N-glycosylated in rodent Panx1. Together, these 
findings indicate that zfPanx1 displays properties similar to its mammalian 
homologues and can potentially play an important role in functions of the outer 
retina.