What are the proteins in a cell membrane?

Question

I need to know their names, and what makes them diferent from the other proteins.I know some names are :Integral, Peripheral, and glycoprotein, but i don't the differences or their other possible names.

Answer 1

The thing that makes membrane proteins different from other proteins is just that they are associated with the membrane.
Around 50% of all proteins are membrane proteins, but they are much harder to isolate intact, and therefore much harder to study.

Integral membrane proteins come in two "flavours". Some - called transmembrane proteins are inserted all the way through the membrane often having multiple stretched of hydrophobic amino acids passing through the membrane, and both an "inside the cell" portion and an "outside the cell" portion. Others (called Integral monotopic membrane proteins) have a lipid tail that anchors them to the membrane (being a "lipoprotein"), or a short tail of hydrophobic amino acids that does this. They will generally only have either an "inside the cell" or an "outside the cell" portion - as they do not stretch the whole way across the membrane.

Peripheral membrane proteins are found associated with the membrane, but are not as tightly -associated as integral membrane proteins. They might bind to another membrane protein (like an integral one), and therefore be next to the membrane. This association is often only temporary and can be turned "on" or "off" by other events. Like the monotopic proteins, they will only be found on one face of the membrane.

Glycoproteins are proteins which have had a carbohydrate added to them. This does not neccessarily make them membrane proteins (for example, many extracellular proteins are glycoproteins), but a lot of "proper" membrane proteins can bind the carbohydrate bits of glycoproteins, keeping the glycoprotein associated as a peripheral membrane protein.

Some example membrane proteins would include:
Receptor proteins in the plasma membrane. These will usually be integral membrane proteins with an extracellular domain that binds the substrate (like a growth factor) and an intracellular domain that changes in structure when the protein binds the substrate, allowing the signal to be propagated to the cell interior.
Often, the intracellular domain of these receptors will have another protein bound to it (a peripheral membrane protein) which might detach, or recruit other proteins in response to the receptor's structure-change.
Pore proteins or ion pumps which allow the transport of ions across the membrane (for example K+ and Na+ pumps and pores are crucial for neuron function). These are also transmembrane proteins.

Read the wikipedia entry for a more in-depth exploration opf the subject.

Answer 2

There are literally 3 forms of cellular membrane proteins: linked ones (loosely related to the membrane), embeded ones (one area is anchored to the membrane) and transmembrane proteins (one area is contained in the cellular one interior the membrane and one protruding) the cellular membrane is a charged lipid bilayer with the detrimental and watery area dealing with out - so any area of a protein beeing interior a membrane must be negatively charged and/or be lipophillic. The domain names of proteins in a membrane or crossing it are many times alpha helices. applications are manifold - for transmembrane proteins the main easy are channel or receptor. Channel transport molecules around the membrane and could be gated to close the cellular - normally a equipment of helices making a small pore. receptors attain for the era of yet make no beginning interior the cellular wall - the perfom a structural substitute upon binding of a ligand which leads to activation contained in the cellular. membrane certain proteins are in many situations places of synthesis or are assisting transmembrane proteins (an occasion may be G- protein coupled receptors) - actually the comparable is going for membrane linked proteins with them beeing able to cycle from and to the membranes (an occasion may be the SecA transporter) easy structures: linked and certain proteines have normally a catalytic center the place they convert ATP or GTP while transmembrane proteins lack those

Answer 3

Integral membrane proteins are permanently attached to the membrane. You need to add soaps to get them out of the membrane. They can be classified according to their relationship with the bilayer:
There functions vary according to their location.

Transmembrane proteins cross the entire membrane, therefore maybe responsible for moving material across it.

Integral proteins are permanently attached to the membrane from only one side, so these may act as receptors, transporters, channels, receptors, enzymes, structural membrane-anchoring,etc.

Peripheral membrane proteins are temporarily attached either to the lipid bilayer or to integral proteins and may also act in a variety of surface functions.

I'm not quite sure of the specific...it's been awhile.

Answer 4

Integral strech all the way through the phospholid bylayer. This allows molecules to flow through.
Peripheral do not go all the way through the bilayer Glycoproteins can have carbohydrates attached which allows for cell communication.

Answer 5

I am not sure about what you are looking for. Maybe this basic concept will help. Most proteins in cell membranes function as either receptors (for signaling molecules such as hormones [e.g. insulin] or cytokines, etc.) or as transporters (ion channels, active transport proteins, etc.).

Best wishes.