What are the functions of the two main components of the plasma membrane?

The two main components of the plasma membrane are lipids and proteins. 

• Lipids, particularly triglycerols and ester steryl stored in liquid droplets also serve as reservoirs for energy storage and as components for building cell membranes. Additionally, lipids in membranes facilitate the formation of organelles, leading to compartmentalization. Lipids also contribute to budding, fission, tubulation, and fusion which are all crucial for cell division and reproduction. Lastly, lipids can act as primary and secondary messengers in signal transduction processes. Amphipathic polar lipids can transmit signals within membranes via their hydrophobic regions and through the cytosol using their soluble regions.  
• Membrane proteins such as ion channels and transport facilitate the movement of ions across membranes. Some membrane proteins also are responsible for electron transport in the mitochondria for example, and enable the production of ATP through oxidative phosphorylation. Receptor proteins in membranes also receive and transmit signals from the exterior of the cell. Upon binding with ligands, these receptors initiate signaling pathways inside cells. Membrane proteins also are involved in cell-cell communication, such as transmembrane proteins.