Proteins - enzymes catalyze a vast array of biochemical reactions.
All membranes contain lipids and proteins.
Lipids provide the basic compartmentalization function of membranes while proteins give membranes their specialized function - transport, signaling, catalysis, etc. Some membranes contain glycoproteins and glycolipids , proteins and lipids combined with carbohydrates. Stable forms Phospholipids take on several types of stable structures in water. Figure 1.14 Size electron micrograph of the plasma membrane of an erythrocyte. The cytoplasm of the erythrocyte is on the left, and extracellular space is on the right.