noun, plural: membrane proteins
Proteins are one of the most essential biomolecules. They serve as structural material, as enzymes, as transporters, as antibodies, or as gene expression regulators. They are made up of polymers comprised of amino acids. They may be classified based on its form and main functions: globular proteins (spheroproteins) like most enzymes, fibrous proteins (scleroproteins) that provide structural support; and membrane proteins that serve as receptors or channels for polar or charged molecule to pass through the cell membrane.
Membrane proteins are those that are found in biological membranes. They are the protein component of plasma membrane and may be classified into: (1) integral membrane proteins and (2) peripheral membrane proteins. The integral membrane proteins are (assembly of) proteins that are permanently attached or firmly anchored in the plasma membrane via their hydrophobic domains interacting with the membrane phospholipids. They may be classified into two major groups: (1) transmembrane proteins, and (2) integral monotropic proteins. The peripheral membrane proteins are proteins that are located at the periphery of the membrane and are temporarily attached to the lipid bilayer.