by Ms. Bernice Rippin V
Published 3 years ago
Updated 2 years ago
Extrinsic or peripheral membrane proteins associate loosely with the hydrophilic surfaces of the lipid bilayer or intrinsic membrane proteins. They form weak hydrophobic, electrostatic or non-covalent bonds, but do not embed with the hydrophobic core of the membrane.
What Kind of Proteins are Found in the Cell Membrane?
Just as a castle is surrounded by a wall, a cell has a membrane that separates the inner cellular 'kingdom' from outside its walls. A castle depends on messengers who bring food and news from the outer world. The same is true for a cell. A cell's messengers are proteins that visit the cell membrane from outside the cell ( extracellular space ).
What Do Membrane Proteins Do?
Let's look at one important function of membrane proteins: receiving news. Receptors are integral proteins in the cell membrane that receive signals from extracellular space so the cell can react. A hormone receptor might get a signal to grow, which sets off a chain of events within the cell called a signalling cascade.
Abstract
The questions. Classical studies by Palade, deDuve, and colleagues established that membranes divide cells into distinct compartments, each with a unique set of resident proteins catalyzing distinct functions. Each compartment is either a membrane, with its own set of embedded proteins, or a soluble space surrounded by a membrane.
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Classifications of Membrane Proteins
Proteins are generally broken down into the smaller classifications of integral proteins, peripheral proteins, and lipid-bound proteins.
Integral Proteins
Integral proteins are embedded within the lipid bilayer. They cannot easily be removed from the cell membrane without the use of harsh detergents that destroy the lipid bilayer. Integral proteins float rather freely within the bilayer, much like oceans in the sea.
Peripheral Proteins
Peripheral proteins are attached to the exterior of the lipid bilayer. They are easily separable from the lipid bilayer, able to be removed without harming the bilayer in any way. Peripheral proteins are less mobile within the lipid bilayer.
Lipid-Bound Proteins
Lipid-bound proteins are located entirely within the boundaries of the lipid bilayer.
The Cell Surface
The protein and lipid cell membrane is covered with a layer of carbohydrate chains on its outer surface. This layer is called a cell coat or glycocalyx. The exact composition and distribution of these chains is very diverse. The chains are thought to provide the cell with protection against damage.
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7.How lipids and proteins interact in a membrane: a …
Url:https://pubmed.ncbi.nlm.nih.gov/16880984/
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Url:https://pubmed.ncbi.nlm.nih.gov/17888630/
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