Membrane protein

A membrane protein is a protein molecule that is attached to, or associated with the membrane of a cell or an organelle.

20–30% of all genes in genomes code for membrane proteins.Krogh A. et al 2001. Predicting transmembrane protein topology with a hidden markov model: application to complete genomes. Journal of Molecular Biology 305 (3): 567–580.  They are targets of over 50% of all modern medicinal drugs.

Function
Membrane proteins perform a variety of functions vital to the survival of organisms:Almén M. et al 2009. Mapping the human membrane proteome: a majority of the human membrane proteins can be classified according to function and evolutionary origin. BMC Biology 7: 50. 
 Membrane receptor proteins relay signals between the cell's internal and external environments.
 Membrane transport proteins move molecules and ions across the membrane.
 Membrane enzymes have many activities.
 Cell adhesion molecules allow cells to identify each other and interact. For example, proteins involved in immune response.

Related pages
 Ion channel

 References 

 Other websites 
 General principles of membrane protein folding and stability   from Stephen White laboratory
 Orientations of proteins in membranes (OPM) database 3D structures of integral and amphitropic membrane proteins

Category:Molecular biology