Consequently, these ubiquitous channels linking neighboring cells have long remained obscure. Not any longer. In the February 6 Nature , the scientists report that mice engineered to lack the gene for one such channel never produce mature eggs because the nurturing cells in the ovarian follicles cannot communicate properly with the oocytes they shelter. Filling in the Gaps Co-author Daniel Goodenough, Takeda Professor of Cell Biology at HMS, first isolated gap junctions biochemically and named their protein subunits connexins. These proteins assemble into tiny tubes in the cell membrane, connect to a similar tube in a neighbor's membrane, and so create a pore through which small molecules can pass from cell to cell.
Gap junctions are everywhere, occurring in all multicellular organisms from sponges on up.
In mammals, cells of almost every tissue make them at some point during development. Researchers suspect that gap junctions are the Baby Bells of the body's communication systems, serving as local distributors of information coming in via long-distance carriers like hormones. In the ovaries, for example, hormones convey messages from the brain, but not all ovarian cells have the necessary receptors. Those that do may use gap junctions to forward the information to their neighbors, says Paul. At the same time, gap junctions are thought to create private communication networks.