Membrane proteins are proteins that are either form part of or interact with cell membranes. Based on their interactions, membrane proteins can be categorized into integral proteins, which are a permanent part of a cell membrane, and peripheral proteins, which adhere temporarily to the cell membrane. Membrane proteins play many critical functions, for example, 1-they are involved in the passive and active transport of substances across cell membranes, 2-act as enzymes that catalyze chemical reactions, 3-act as receptors that bind specific molecules (such as hormones or neurotransmitters) in order to activate signaling cascades, 4-mediate communication between cells, 5-provide a mechanical link between the extracellular matrix and the cytoskeleton, etc.
