How do proteins contribute to the functions of the cell membrane?
The cell membrane is the outer part of the cell involved in cell to cell signalling. Proteins embedded in the membrane bind to a signal ligand and change. This change allows a process in the cell to begin.
There are also barrels of beta protein sheets stuck in the membrane. They have a polar hydrophobic inside and a hydrophilic outside. They allow molecules to enter the membrane. These are simple transport mechanisms. Proteins also act as parts to larger transport mechanisms such as pumps.
Proteins also can be sticky, and help the cell adhere to different surfaces. Specifically N linked glycoprotiens are able to create cell to cell adhesion.