A transmembrane protein (TP) is a type of integral membrane protein that spans the entirety of the cell membrane. Many transmembrane proteins function as gateways to permit the transport of specific substances across the membrane. They frequently undergo significant conformational changes to move a substance through the membrane. They are usually highly hydrophobic and aggregate and precipitate in water. They require detergents or nonpolar solvents for extraction, although some of them (beta-barrels) can be also extracted using denaturing agents.
The peptide sequence that spans the membrane, or the transmembrane segment, is largely hydrophobic and can be visualized using the hydropathy plot. Depending on the number of transmembrane segments, transmembrane proteins can be classified as single-span (or bitopic) or multi-span (polytopic). Some other integral membrane proteins are called monotopic, meaning that they are also permanently attached to the membrane, but do not pass through it.
There are two basic types of transmembrane proteins: alpha-helical and beta barrels. Alpha-helical proteins are present in the inner membranes of bacterial cells or the plasma membrane of eukaryotic cells, and sometimes in the bacterial outer membrane. This is the major category of transmembrane proteins. In humans, 27% of all proteins have been estimated to be alpha-helical membrane proteins.
Beta-barrel proteins are so far found only in outer membranes of gram-negative bacteria, cell walls of gram-positive bacteria, outer membranes of mitochondria and chloroplasts, or can be secreted as pore-forming toxins. All beta-barrel transmembrane proteins have simplest up-and-down topology, which may reflect their common evolutionary origin and similar folding mechanism.
In addition to the protein domains, there are unusual transmembrane elements formed by peptides. A typical example is gramicidin A, a peptide that forms a dimeric transmembrane β-helix. This peptide is secreted by gram-positive bacteria as an antibiotic.
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Membrane organization.
Investigate the compartmentalisation of biological membranes: what are the determinants of the localization of transmembrane proteins in the 2 dimensional space of the membranes
This course is aimed to familiarize students with the 3D organization of a eukaryotic cell, its compartmentalization, how cellular compartments communicate together and how a cell communicates with it
Cryo-electron microscopy structural analysis of proteins. The course aims at demonstrating the workflow from sample purification to determining the atomic structure of a soluble or membrane protein.
Learn about how the quality of water is a direct result of complex bio-geo-chemical interactions, and about how to use these processes to mitigate water quality issues.
A transmembrane protein (TP) is a type of integral membrane protein that spans the entirety of the cell membrane. Many transmembrane proteins function as gateways to permit the transport of specific substances across the membrane. They frequently undergo significant conformational changes to move a substance through the membrane. They are usually highly hydrophobic and aggregate and precipitate in water. They require detergents or nonpolar solvents for extraction, although some of them (beta-barrels) can be also extracted using denaturing agents.
The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extracellular space). The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols (a lipid component) interspersed between them, maintaining appropriate membrane fluidity at various temperatures.
A proton pump is an integral membrane protein pump that builds up a proton gradient across a biological membrane. Proton pumps catalyze the following reaction: H+[on one side of a biological membrane] + energy H+[on the other side of the membrane] Mechanisms are based on energy-induced conformational changes of the protein structure or on the Q cycle. During evolution, proton pumps have arisen independently on multiple occasions. Thus, not only throughout nature but also within single cells, different proton pumps that are evolutionarily unrelated can be found.
Explores membrane protein quality control mechanisms at the ER, focusing on ERAD recognition, retrotranslocation, ubiquitination, and degradation of misfolded proteins.
DNA nanotechnology has emerged as a promising method for designing spontaneously inserting and fully controllable synthetic ion channels. However, both insertion efficiency and stability of existing D
Nanodiscs offer a very promising tool to incorporate membrane proteins into native-like lipid bilayers and an alternative to liposomes to maintain protein functions and protein-lipid interactions in a
The use of tractable model organisms such as Drosophila melanogaster and the powerful genetic tools they offer has contributed significantly to recent advances in comprehension of innate immunity, not