Protein topology is a property of protein molecule that does not change under deformation (without cutting or breaking a bond). In biology literature, the term topology is also used to refer to mutual orientation of regular secondary structures, such as alpha-helices and beta strands in protein structure [1].
Is the lipid bilayer hydrophobic?
A lipid bilayer is a biological membrane consisting of two layers of lipid molecules. Each lipid molecule, or phospholipid, contains a hydrophilic head and a hydrophobic tail. The inside of the lipid bilayer is non-polar, while the heads are polar molecules and create hydrogen bonds with other polar molecules.
How do you cite Pdbsum?
PDBsum is a database that provides an overview of the contents of each 3D macromolecular structure deposited in the Protein Data Bank….PDBsum.
| Content | |
|---|---|
| Authors | Roman Laskowski & al. (1997) |
| Primary citation | PMID 9433130 |
| Access | |
| Website |
What is the hierarchy of protein structure?
The four levels of protein structure are primary, secondary, tertiary, and quaternary.
What is the purpose of an integral protein?
Integral membrane proteins are permanently embedded within the plasma membrane. They have a range of important functions. Such functions include channeling or transporting molecules across the membrane. Other integral proteins act as cell receptors.
What is the topology of a membrane protein?
The topology of a membrane protein was just a description, listing the segments of the polypeptide chain that form the transmembrane helices and their orientation relative to the membrane. But now, 6 years on and 60 high-resolution membrane-protein structures later, the picture is not so simple.
What is a cytoplasmic topology?
Topologies in which both the N terminus and the C terminus of a protein are in the cytoplasm are predominant in both prokaryotic and eukaryotic cells. Membrane proteins evolve primarily by gene duplication and gene fusion.
How is topology of transmembrane helices determined?
Topology is controlled primarily by the hydrophobicity and length of transmembrane helices as well as the distribution of positively charged residues in the loops that connect the helices. In most cases, topology is determined co-translationally during the translocon-mediated insertion of a polypeptide into a membrane.
Are membrane proteins dynamic or static?
In summary, membrane proteins can be dynamic entities, with their transmembrane helices changing position in the membrane, partially folding and unfolding, and repacking during a reaction cycle. However, there is no clear case in which the basic topology of a protein changes as the protein cycles between different conformational states.
