Now what about this? Well, this is not actually part of that glycolytic pathway, but it's very close to glyceroaldehyde three phosphate. The only thing it's missing is of a sporal group on carbon number three. And so all we have to do in the third step is use a special enzyme and an ATP molecule to basically attach a phosphoryl onto carbon number three. And that's exactly what trio's kinase actually does. Now trio simply means this substrate molecule is a three carbon sugar.