Glutenin (sometimes known as glutenine) is the name of the glutelin protein found in wheat. Gluten consists of prolamin and glutelin. Wheat gluten consists, in part, of glutenin.
Glutenin is not generally considered the primary culprit when it comes to triggering celiac disease, although it may be part of the reaction.
For someone with a gluten allergy, the specific component of gluten they may be reacting to probably varies from one person to the other.
Glutenin creates disolfide bonds with other proteins including gluten. This is what provides dough made of wheat and other high-gluten grains their desirable properties including firmness, elasticity and cohesion.
In practice, it seems that there is no separating glutenin from prolamin (specifically gliadin in the case of wheat), so this information is more of technical interest than it is of practical importance to someone with celiac disease.However there may be practical cases where the above is possible.
There is research being conducted by Dr. Diter von Wettstein to breed mutant wheat plants that produce only glutenin and no gliadin. This may produce a kind of wheat that celiacs can tolerate. If wheat with glutenin but without gliadin can be produced, and turns out not to effect celiacs, new baking opportunities may arise, assuming an uncontaminated source of this specialized wheat can be relied upon.
This may also help certain people with a gluten allergy, depending on what component of gluten they are allergic to.