Basis of differentiation 

Integral proteins

Peripheral proteins

Definition 

Are proteins that are tightly and permanently attached to the plasma membrane

Are proteins that are loosely and temporarily attached to the plasma membrane

Location 

Are fully or partially embedded in the lipid layer of the plasma membrane

Are located on the innermost or outermost surface of the plasma membrane

Also known as

Intrinsic proteins

Extrinsic proteins

Constituent of the Membrane Protein

Make up 70% of the total membrane proteins

Make up 30% of the total membrane proteins

Hydrophilic/Hydrophobic

Contain both hydrophilic and hydrophobic parts

Contain hydrophilic parts only

Function

Serve as carrier proteins, enzymes, and channel proteins

Serve as receptors

Interaction with the hydrophobic core of the lipid bilayer

High level of interaction 

Low level of interaction 

Types of Interactions with Lipid Bilayer

Bind to the lipid bilayer by electrostatic, hydrophobic, or non-covalent interactions

Peripheral proteins on the inner surface of the lipid bilayer are held by the cytoskeleton

Protein Removal

• Are more difficult to  remove from the plasma membrane because of the stronger bonds
• Requires detergents to break the strong hydrophobic bonds and remove integral proteins from the plasma membrane

• Are easier to remove from the plasma membrane because of the weaker bonds
• Dilute salt solutions are effective to remove peripheral proteins from the plasma membrane 

After removal

Cannot be dissolved in neutral aqueous buffers or aggregates

Can be dissolved in neutral aqueous buffers

Examples

• Glycophorin
• Rhodopsin 
• NADH dehydrogenase 

• Mitochondrial cytochrome c 
• Erythrocyte spectrin