Membrane protein, compared with other proteins, may not be that unusual to researchers, but it is undeniably irreplaceable in the world of biology. Even though, how much do you know about membrane protein?
What is membrane protein?
Membrane proteins are proteins that interact with biological membranes. They are targets of over 50% of all modern medicinal drugs. It is estimated that 20–30% of all genes in most genomes encode membrane proteins.
The function of membrane protein varies.
As their name suggests, membrane proteins are anchored in membranes. Each of them, however has a specific function, and that function often requires them to extend beyond the membrane. Some membrane proteins sit on the surface. Others are anchored in the membrane and have pieces (called domains) on one or both sides of it.
Proteins with extracellular areas (which means they’re outside the cell) typically contain cell-to-cell correspondences or associations. Proteins that stand fundamentally inside a membrane usually form channels or pores to help particles cross the membrane. Proteins with cytosolic areas (which means they’re inside the cell) have the most extensive scope of capacity. For example, they can be anchors for cytoskeletal (cell skeleton) proteins or involved with intracellular signaling.
Membrane receptor proteins relay signals between the cell’s internal and external environments. Transport proteins move molecules and ions across the membrane. They can be categorized according to the Transporter Classification database. Membrane enzymes may have many activities, such as oxidoreductase, transferase or hydrolase. Cell adhesion molecules allow cells to identify each other and interact, proteins involved in immune response, for instance.
Types and Structures of Membrane Protein
The structure of membrane proteins can always tell their function, which, in return explains the way we group the type of membrane protein.
Peripheral Membrane Protein
Peripheral membrane protein usually attaches to integral membrane proteins, or penetrates the peripheral regions of the lipid bilayer. The regulatory protein subunits of many ion channels and transmembrane receptors, for example, may be defined as peripheral membrane proteins. Copmared with integral membrane protein, peripheral membrane protein tends to collect in the water-soluble component, or fraction, of all the proteins extracted during a protein purification procedure. Proteins with GPI anchors are an exception to this rule and can have purification properties similar to that of integral membrane proteins.
Integral Membrane Protein
Integral or intrinsic membrane protein has one or more domains that are embedded in the membrane. The embedded regions are made of amino acids with hydrophobic side chains. As such, they want to be snuggled up with the hydrophobic part of the membrane. This anchors the protein in the membrane. Integral membrane proteins can have hydrophilic domains that extend into the extracellular or intracellular aqueous environment. Most have both and are, therefore, called transmembrane proteins.
Polypeptide toxin and many antibacterial peptide, such as colicin or hemolysin, and certain proteins involved in apoptosis, are sometimes considered a separate category. These proteins are water-soluble but can aggregate and associate irreversibly with the lipid bilayer and become reversibly or irreversibly membrane-associated.
Because of the important role membrane protein plays in the biological world, more and more institutes as well as industries are doing research on it, Creative Biolabs, for instance. Like other leading biotech related service provider, Creative Biolabs is devoting increasing time and effort to this field, so as to offer researches the most reliable service in deeper study of membrane protein.