Complete the paragraph that follows:Many proteins are controlled byregulation , where a ligand binds to part of the protein other than the active site. Others are subject tocovalent modification with phosphoryl, methyl, or other functional groups that affect protein activity. The activity of GTP-binding (G) proteins is dependent on whether they have GTP orbound to them. G proteins are one example of a, where the same protein can exist in either of two stable states that have alternate activities.1. irreversible.2. coenzyme allosteric GDP molecular switch. 3. reversible prosthetic ATP.