What are the differences between integral and peripheral proteins?

Question

Accepted Answer

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

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

After removal

Examples

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