Walter and Eliza Hall Institute scientists have determined the structure of a previously unseen part of the insulin receptor, making way for new possible diabetes treatments.

The insulin receptor, a large protein on cell's surface, binds to insulin hormone. The control of glucose and how it is used in the human body is regulated by insulin. The key to developing new treatment for diabetes lies in the understanding of how insulin interacts with the insulin receptor.

In 2006, Australian scientists have revealed the structure of the major part of the insulin, but the structure of the key element which binds with insulin remained elusive.

Now, the molecular structure of this previously unseen region have been discovered by Drs Mike Lawrence, Brian Smith, John Menting, Geoffrey Kong and Colin Ward from the institute's Structural Biology division together with researchers from the Case Western Reverse University and University of Chicago.

For decades, scientists have been trying to work out how insulin interacts with the insulin receptor, said Dr Lawrence.

You can't work it out unless you have a view of the site to which the insulin binds, and that's what we've done, he said.

By understanding how insulin binds and transmits messages into the cell we will be in a better position to design compounds that mimic insulin and could be used to treat diabetes.

The team is also trying to find out the structure of the related Type 1 insulin-like growth factor receptor, to which the insulin-like growth factors bind.

These structures are not currently known, despite their considerable importance and direct relevance to the design of new drugs for cancer, Alzheimer's disease and diabetes - three of the most critical disease facing Australia, said Dr Lawrence.

The findings of the research have been published in the Proceedings of the National Academy of Sciences USA early edition.