Dodecamer
Encyclopedia
Dodecameric is a term pertaining to protein
quaternary structure
, and describes a protein complex
with 12 protein subunits (protein chains). Dodecameric complexes can have a number of subunit
'topologies
', but typically only a few of the theoretically
possible subunit arrangement
s are observed in protein structure
s.
A dodecamer is a protein complex with 12 protein subunits.
A common subunit
arrangement involves a tetrahedral distribution of subunit trimers (or 3-4-point symmetry
). Another observed arrangement of subunits
puts two rings of six subunits side by side along the six fold axis (or 2-6-point symmetry).
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
quaternary structure
Quaternary structure
In biochemistry, quaternary structure is the arrangement of multiple folded protein or coiling protein molecules in a multi-subunit complex.-Description and examples:...
, and describes a protein complex
Protein complex
A multiprotein complex is a group of two or more associated polypeptide chains. If the different polypeptide chains contain different protein domain, the resulting multiprotein complex can have multiple catalytic functions...
with 12 protein subunits (protein chains). Dodecameric complexes can have a number of subunit
Protein subunit
In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles with other protein molecules to form a protein complex: a multimeric or oligomeric protein. Many naturally occurring proteins and enzymes are multimeric...
'topologies
Topology
Topology is a major area of mathematics concerned with properties that are preserved under continuous deformations of objects, such as deformations that involve stretching, but no tearing or gluing...
', but typically only a few of the theoretically
Theory
The English word theory was derived from a technical term in Ancient Greek philosophy. The word theoria, , meant "a looking at, viewing, beholding", and referring to contemplation or speculation, as opposed to action...
possible subunit arrangement
Arrangement
The American Federation of Musicians defines arranging as "the art of preparing and adapting an already written composition for presentation in other than its original form. An arrangement may include reharmonization, paraphrasing, and/or development of a composition, so that it fully represents...
s are observed in protein structure
Protein structure
Proteins are an important class of biological macromolecules present in all organisms. Proteins are polymers of amino acids. Classified by their physical size, proteins are nanoparticles . Each protein polymer – also known as a polypeptide – consists of a sequence formed from 20 possible L-α-amino...
s.
A dodecamer is a protein complex with 12 protein subunits.
A common subunit
Protein subunit
In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles with other protein molecules to form a protein complex: a multimeric or oligomeric protein. Many naturally occurring proteins and enzymes are multimeric...
arrangement involves a tetrahedral distribution of subunit trimers (or 3-4-point symmetry
Point groups in three dimensions
In geometry, a point group in three dimensions is an isometry group in three dimensions that leaves the origin fixed, or correspondingly, an isometry group of a sphere. It is a subgroup of the orthogonal group O, the group of all isometries that leave the origin fixed, or correspondingly, the group...
). Another observed arrangement of subunits
Protein subunit
In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles with other protein molecules to form a protein complex: a multimeric or oligomeric protein. Many naturally occurring proteins and enzymes are multimeric...
puts two rings of six subunits side by side along the six fold axis (or 2-6-point symmetry).
Dodecameric proteins include
- Complete gap junctionGap junctionA gap junction or nexus is a specialized intercellular connection between a multitude of animal cell-types. It directly connects the cytoplasm of two cells, which allows various molecules and ions to pass freely between cells....
channel, composed of two hexamers. - glutamine synthetaseGlutamine synthetaseGlutamine synthetase is an enzyme that plays an essential role in the metabolism of nitrogen by catalyzing the condensation of glutamate and ammonia to form glutamine:Glutamate + ATP + NH3 → Glutamine + ADP + phosphate...
(PDB code: 2gls) - Dodecameric ferritinFerritinFerritin is a ubiquitous intracellular protein that stores iron and releases it in a controlled fashion. The amount of ferritin stored reflects the amount of iron stored. The protein is produced by almost all living organisms, including bacteria, algae and higher plants, and animals...
(PDB code: 1qgh) - Aβ42 - Amyloid-beta 42