Editing Biological membrane (section)

=== Proteins ===
[[Phospholipid bilayer]]s contain different proteins. These [[membrane protein]]s have various functions and characteristics and catalyze different chemical reactions. Integral proteins span the membranes with different domains on either side.<ref name=":0" /> Integral proteins hold strong association with the lipid bilayer and cannot easily become detached.<ref name=":7" /> They will dissociate only with chemical treatment that breaks the membrane. Peripheral proteins are unlike integral proteins in that they hold weak interactions with the surface of the bilayer and can easily become dissociated from the membrane.<ref name=":0" /> Peripheral proteins are located on only one face of a membrane and create membrane asymmetry.
{| class="wikitable sortable"
|+SOME EXAMPLES OF PLASMA MEMBRANE PROTEINS AND THEIR FUNCTIONS
!FUNCTIONAL CLASS
!PROTEIN EXAMPLE
!SPECIFIC FUNCTION
|-
|Transporters
|[[Na+/K+-ATPase|Na<sup>+</sup> pump]]
|actively pumps Na<sup>+</sup> out of cells and K<sup>+</sup> in
|-
|Anchors
|[[integrin]]s
|link intracellular actin filaments to extracellular matrix proteins
|-
|Receptors
|[[platelet-derived growth factor]] receptor
|binds extracellular PDGF and, as a consequence, generates intracellular signals that cause the cell to grow and divide
|-
|Enzymes
|[[adenylyl cyclase]]
|catalyzes the production of intracellular signaling molecule cyclic AMP in response to extracellular signals
|}