Integral membrane proteins

Integral membrane proteins are those which are embedded directly into the phospholipid bilayer cell membrane. Although all highly specific, they can be placed into one of three categories:

Proteins which are embedded only into the inner leaflet of the phospholipid bilayer membrane. 

2. Cell Surface Proteins Proteins which are embedded only into the outer leaflet of the phospholipid bilayer membrane.

3. Transmembrane Proteins Proteins which span the entire phospholipid bilayer membrane, from the cytosol to the exterior of the cell.

All integral membrane proteins can be released from the cell membrane by the use of a detergent.

Most integral proteins are either alpha helices, which can be single or multipass, or beta sheets which form a pore like structure through the membrane as a beta barrel.