Kuiper Belt : Neptune's Influence :: Oort Cloud : ?

The Kuiper Belt is a region of icy bodies that is kept in its current shape mainly by the gravitational pull of Neptune, which nudges and shepherds the objects. Similarly, the Oort Cloud is a distant sphere of comets that is largely held together and shaped by the Sun’s gravity, which keeps the comets bound to the Solar System. In both cases the outer structure is controlled by a single, massive body. For example, just as Neptune’s orbit sets the Kuiper Belt’s edge, the Sun’s gravity keeps the Oort Cloud’s comets from drifting away. Thus the analogous pair is “Oort Cloud : Sun.