Distribution of Ogre, Inx2, Inx3 and Zpg in the follicle.
A diagram of the complete follicle is shown (lower image) with a close-up representation (upper image) revealing the distibution of innexin proteins in three cell types. The oocyte expresses Inx2 (green) and Zpg/Inx4 (blue) which are located in the oolemma - the membrane surrounding the oocyte. Nurse cells posses Inx2 (green), Inx3 (purple) and Zpg/Inx4 (blue) in the plasma membrane. Follicle cells (fc) possess Ogre (red), Inx2 (green) and Inx3 (purple) in the plasma membrane but they do not contain any of the germ cell-specific Zpg/Inx4 protein. Ogre (red) in follicle cells is restricted to the baso-lateral domain where it may interact with Inx2 (green) and/or Inx3 (purple). A myc-tagged Ogre protein appears to co-localize with Inx2 and Inx3 in other tissues such as the pupal salivary glands and in adult brain glia. Messenger RNA from inx7 is also detected in the follicle but it’s not known if the protein product is synthesised here. This image is a summary of some of the information published by Bohrmann and Zimmermann, 2008.