Structural components of the gap junctions. Involved in gap junctional communication between germline and somatic cells which is essential for normal oogenesis. In embryonic epidermis, required for epithelial morphogenesis. Required for keyhole formation during early stages of proventriculus development in response to wg signaling. In follicle cells, promotes the formation of egg chambers in part through regulation of shg and baz at the boundary between germ cells and follicle cells. In inner germarial sheath cells, required for survival of early germ cells and for cyst formation. Monomer and heterooligomer with ogre or Inx3 (via cytoplasmic C-terminal region). Interacts (via cytoplasmic loop) with shg (via cytoplasmic region). Interacts with arm. In ovary, localizes to the apicolateral membrane between follicle cells and to the apical membrane between follicle cells and germline cells. Accumulates in the apicolateral membrane of epithelial cells in the epidermis. In salivary gland cells, accumulates in the basolateral membrane. In hindgut epithelial cells, accumulates in the lateral membrane. In nurse cells, localizes around the nuclei at oogenesis stage 10a and then, during stages 10b and 11, in cytoplasmic clouds and particles which become delivered into the oocyte during nurse cell regression. In ovary, expressed in inner germarial sheath cells, prefollicular cells, follicle cells, nurse cells and oocytes. Expressed in embryonic epithelial cells. Expressed in foregut and hindgut from stage 11-17, segmentally repeated tracheal placodes at stage 14, salivary gland at stage 16 and proventriculus at stage 16-17 (at protein level). During germband extension stage (stage 7), expressed in epidermal epithelial cells. Expressed in cephalic furrow. Repeating epidermal pattern emerges at stage 11, refines to one or two cells at each side of the segment borders by stage 13. Expressed in the imaginal wing disk. In pupae, expressed in the CNS and in primary, secondary and tertiary pigment cells of the retina. Expressed in optic lamina of the adult CNS. Expressed maternally and zygotically. Expressed during oogenesis and embryogenesis. Expressed in larvae and pupae. Expression in embryos at ectoderm/endoderm boundaries during gut organogenesis is induced by activation of the wg signaling cascade. Female sterility. Only one third of the zygotic mutant embryos survive up to the first instar larval stage. These mutant larvae display a feeding defect most probably caused by a keyhole formation defect during proventriculus development. The feeding defect may result in larvae death by starvation. Zygotic mutant embryos display large holes in the head region and a variable spectrum of segment defects. In maternal and zygotic mutant embryos, epithelial tissues and organs are severely affected, the cuticle fails to form and extensive cell death occurs. Belongs to the pannexin family.