Before revision:  At the biological level, such membrane domains have been demonstrated to be specialized, in that sense that they congregate one or a few protein species amongst the hundreds of different species that a cell membrane may contain , in order to perform a determined biological task .
After revision:  At the biological level, such membrane domains have been demonstrated to be specialized, in that sense that they congregate one or a few protein species out of the hundreds of different species that a cell membrane may contain , in order to perform a determined biological task .