Extrinsic Protein vs. Integral Protein

Attribute	Extrinsic Protein	Integral Protein
Location in cell membrane	Located on the surface of the cell membrane	Embedded within the cell membrane
Function	Often involved in cell signaling and cell-cell recognition	Can act as channels or transporters for molecules across the membrane
Structure	Do not span the entire lipid bilayer	Span the entire lipid bilayer
Attachment to membrane	Attached to the membrane by interactions with integral proteins or lipids	Directly attached to the lipid bilayer

Structure

Extrinsic proteins, also known as peripheral proteins, are proteins that are attached to the surface of the cell membrane. They do not penetrate the lipid bilayer and are easily removed without disrupting the membrane. In contrast, integral proteins are embedded within the lipid bilayer of the cell membrane. They have hydrophobic regions that interact with the hydrophobic tails of the phospholipids, anchoring them in place.

Function

Extrinsic proteins often serve as receptors or enzymes that facilitate cell signaling and communication. They can also act as markers for cell recognition and adhesion. Integral proteins, on the other hand, play a crucial role in transporting molecules across the cell membrane. They can form channels or carriers that allow specific substances to pass through the membrane.

Location

Extrinsic proteins are found on the surface of the cell membrane, where they interact with the extracellular environment. They are easily detached from the membrane and can be solubilized with mild detergents. Integral proteins, on the other hand, are firmly embedded within the lipid bilayer and cannot be easily removed without disrupting the membrane structure.

Structure

Extrinsic proteins are typically globular in shape and have hydrophilic regions that interact with the aqueous environment outside the cell. They are often attached to the membrane through interactions with integral proteins or lipids. Integral proteins, on the other hand, have a more elongated shape with hydrophobic regions that span the lipid bilayer. This structure allows them to form channels or transporters for specific molecules.

Function

Extrinsic proteins are involved in cell signaling, adhesion, and recognition. They can bind to ligands or other proteins on the cell surface to initiate a signaling cascade. Integral proteins, on the other hand, are essential for maintaining the integrity of the cell membrane and regulating the passage of molecules in and out of the cell. They can be selective in the substances they transport, allowing for precise control of cellular processes.

Location

Extrinsic proteins are found on the outer surface of the cell membrane, where they interact with the extracellular environment. They can be easily removed from the membrane without disrupting its structure. Integral proteins, on the other hand, are embedded within the lipid bilayer and are essential for the structural integrity of the membrane. They cannot be easily detached without affecting the membrane's function.