How to serialize a gameobject using binaryformatter?

I'm having a problem with when I try to serialize a list of ItemClasses, it has a problem with the gameobject, saying that UnityEngine.GameObject is not marked a serializable?

ItemClass Script (It's quite complex, the gameobject variable is at the bottom):

 public class ItemClass
 {
     var Name : String;
     var ID : int;
     var Weight : float = 5;
         
     var Quantity : int = 1;
     var Value : int = 100;
     enum ItemTypeEnum {Weapon, Apparel, Book, Scroll, Potion, Ingredient, Food, Miscellaneous}
     var ItemType : ItemTypeEnum;
     enum WeaponCategoryEnum {OneHanded, TwoHanded, Dagger, Throwing, Staff, Bow}
     var WeaponCategory : WeaponCategoryEnum;
     enum WeaponTypeEnum {Sword, Axe, Mace, Flail, GreatSword, BattleAxe, WarHammer, Spear, ThrowingKnife, ThrowingAxe, ThrowingDart, Magical, Martial, Longbow, Recurve}
     var WeaponType : WeaponTypeEnum;
     enum ApparelTypeEnum {LightArmour, HeavyArmour, Clothing}
     var ApparelType : ApparelTypeEnum;
     enum ApparelLocationEnum {Head, Torso, Hands, Legs, Feet, Rings, Face}
     var ApparelLocation : ApparelLocationEnum;
     enum BookTypeEnum {Blank, Written, Enchanted}
     var BookType : BookTypeEnum;
     enum ScrollTypeEnum {Blank, Enchanted, Inscribed}
     var ScrollType : ScrollTypeEnum;
     var Damage : float = 10;
     var Protection : float = 5;
     enum EnchantmentEnum {Unenchanted, Sharpness, FireDamage, IceDamage, ShockDamage, StealHealth, StealStamina, StealMana, AddedProtection, DamageRebound}
     var Enchantment : EnchantmentEnum;
     var EnchantStrength : int = 1;
     var EnchantDuration : float = 5;
     enum PotionTypeEnum {InstantHealth, HealthRegen, AttackDamageIncrease, Strength, Defence, InstantMana, ManaRegen}
     var PotionType : PotionTypeEnum;
     var PotionStrength : int = 25;
     var PotionDuration : float = 15;
     var Representation : GameObject;
 }

Any ideas? :)