There are two ways membrane proteins can be classified based on their different characteristics. 

Based on duration of membrane association, membrane proteins can be classified as:

• Integral membrane proteins, which are firmly and permanently attached to the lipid bilayer
• Peripheral membrane proteins, which are loosely and temporarily attached to the membrane or to integral membrane proteins

Based on mode of membrane association, membrane proteins can be classified as: 

• Transmembrane proteins, or bitopic proteins, which cross the membrane layer at least once
• Monotopic membrane proteins, which are attached to one side of the lipid bilayer and can interact with the membrane in different ways