In molecular biology, a protein domain is a region of a protein's polypeptide chain that is self-stabilizing and that folds independently from the rest. Each domain forms a compact folded three-dimensional structure. Many proteins consist of several domains, and a domain may appear in a variety of different proteins. Molecular evolution uses domains as building blocks and these may be recombined in different arrangements to create proteins with different functions. In general, domains vary in length from between about 50 amino acids up to 250 amino acids in length. Molecular evolution gives rise to families of related proteins with similar sequence and structure. However, sequence similarities can be extremely low between proteins that share the same structure. Protein structures may be similar because proteins have diverged from a common ancestor. Alternatively, some folds may be more favored than others as they represent stable arrangements of secondary structures and some proteins may converge towards these folds over the course of evolution. Domain swapping is a mechanism for forming oligomeric assemblies.[31] In domain swapping, a secondary or tertiary element of a monomeric protein is replaced by the same element of another protein. Domain swapping can range from secondary structure elements to whole structural domains. It also represents a model of evolution for functional adaptation by oligomerisation, e.g. oligomeric enzymes that have their active site at subunit interfaces. Here you have a striking example of the domain-swapping phenomenon, illustrated by Monellin, a poly-glutamate rich protein isolated from the tropical plant Dioscoreophyllum cumminsii (PDB code: 7VWW)
#molecularart ... #immolecular ... #domain ... #swapping ... #quarternary ... #xray ... #glutamate
Structure rendered with @proteinimaging and depicted with @corelphotopaint
#molecularart ... #immolecular ... #domain ... #swapping ... #quarternary ... #xray ... #glutamate
Structure rendered with @proteinimaging and depicted with @corelphotopaint
