Peripheral protein

Peripheral proteins are a type of protein that adhere only temporarily to the biological membrane with which they are associated. These proteins attach to integral membrane proteins, or penetrate the peripheral regions of the lipid bilayer. The function of these proteins is primarily to connect the cell membrane to other structures, like the cytoskeleton.

Structure and Function

Peripheral proteins are not embedded within the lipid bilayer at all; rather they are strongly bound to the surfaces of the membrane and are associated with it only temporarily. They can be easily removed without disrupting the membrane structure.

The functions of peripheral proteins are varied. They often serve as enzymes, as anchors for the cell cytoskeleton, or as part of the cell's signal transduction mechanisms. They are often involved in the gathering of cell signaling information, which is then communicated to the interior of the cell for cellular responses to be activated.

Interaction with Lipid Bilayer

Peripheral proteins interact with the lipid bilayer by way of ionic interactions and hydrogen bonds, both of which can occur at the lipid bilayer surface. These interactions are often mediated by lipid anchors like prenyl groups, glycosylphosphatidylinositol, myristoyl groups, and palmitoyl groups.

Examples

Examples of peripheral proteins include spectrin, a large protein that attaches to the membrane by interacting with integral proteins and helps to maintain the shape of red blood cells, and G proteins, which are involved in cell signaling.

See Also

• Integral protein
• Transmembrane protein
• Lipid bilayer
• Cell membrane

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