Ob-Rb, is expressed at a high level in the hypothalamus. Ob-Re, is produced in fat tissue and encodes a secreted form of the receptor, which may be a carrier protein for leptin.
More research is required to define the functions of the other forms of the leptin receptor.
In 1995, the Millennium group led by Louis Tartaglia, Ph.D., cloned a leptin receptor, Ob-R, from the brain's choroid plexus. This brain structure makes the cerebrospinal fluid that bathes the brain and spinal column. They identified Ob-R by virtue of its ability to bind to leptin, the hormone made by the mouse obese gene, which Friedman and his colleagues isolated and cloned in 1994. The Millennium team also identified a second form of the receptor that is the human equivalent to Ob-Rb. In the current work reported in Nature , Friedman and his team identified at least six different forms of the Ob-R protein and propose that many additional forms of this receptor exist.