Researchers have discovered that cone snails use a modified form of insulin when hunting prey. The discovery may aid in the development of improved synthetic insulin compounds. The findings are in a paper that was just published in the journal Nature Structural & Molecular Biology.
The geography cone (Conus geographus) is a species of predatory cone snail. Like most cone snails, geography cones catch and feed on small reef fish. They possess venom that is toxic enough to kill humans. A recent discovery showed that they used a second chemical to stun their prey—a form of insulin. Cone snails release a modified version of insulin that is rapidly absorbed through the gills of fish. The overload of insulin puts the fish into hypoglycemic shock, allowing for easy capture.
The form of insulin used by the geography cone snail has a unique structure. The B region of human insulin contains a chain that allows multiple insulin molecules to bond together. This helps the body store insulin in the pancreas. When dosing a diabetes patient, however, the insulin isn’t helpful until it separates back into individual molecules. Even the fastest synthetic insulin available can take up to 30 minutes to take effect. The insulin used by the cone snail, however, lacks the section of the B region that causes problems. Interestingly, the absence of the region doesn’t significantly affect the potency of the insulin. When scientists have tried to remove the same region in human insulin, the compound stopped working.
Researchers from the University of Utah tested the cone snail insulin on human insulin receptors. While the insulin was less effective than current synthetic versions, it still worked properly and took effect within 5 minutes. The team is hoping to use their findings to improve synthetic insulin by making it structurally similar to the compound used by cone snails. A fast-acting form of insulin has the potential to save lives and can also be used in artificial pancreas development.
John G Menting et al. A minimized human insulin-receptor-binding motif revealed in a Conus geographus venom insulin. Nature Structural & Molecular Biology (2016).