What is the role of proteins within a plasma membrane?

Membrane proteins mediate actions that are critical to the survival of biological cells. Membrane-embedded transporters carry ions and bigger solutes across membranes, receptors facilitate cell-to-cell communication, and membrane-embedded enzymes catalyse chemical processes.

Mnemonic (JET RAT)

Junctions – Serve to connect and join two cells together 

Enzymes – Fixing to membranes localises metabolic pathways 

Transport – Responsible for facilitated diffusion and active transport 

Recognition – May function as markers for cellular identification 

Anchorage – Attachment points for cytoskeleton and extracellular matrix 

Transduction – Function as receptors for peptide hormones

Proteins have many roles within a plasma membrane. Proteins in the form of carrier proteins are involved in active transport of molecules both in and out of a cell. Porteins in the form of channel proteins are involved in the passive transport of molecules down the concentration gradient (either in or out of the cell). Proteins can also play a key role in cell adhesion (glycoproteins) or cell signalling (glycoproteins).