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In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles (or "coassembles") with other protein molecules to form a multimeric or oligomeric protein. Many naturally occurring proteins and enzymes are multimeric. Examples include hemoglobin, ion channels, DNA polymerase, nucleosomes and microtubules. The subunits of a multimeric protein may be identical, homologous or totally dissimilar and dedicated to disparate tasks. In some protein assemblies, one subunit may be referred to as a " regulatory subunit " and another as a " catalytic subunit ." An enzyme composed of both regulatory and catalytic subunits when assembled is often referred to as a holoenzyme.

One subunit is made of one polypeptide chain. A polypedtide chain have one gene coding for it - that means a protein needs to have one gene for each subunit.

A subunit is often named with a greek or roman letter, and the numbers of this type of subunit in a protein is indicated by a subscript. For example, ATP synthase has a type of subunit called α. Three of these are present in the ATP synthase molecule, and is therefore designated α₃. Larger groups of subunits can also the specified, like α₃β₃-hexamer and c-ring.

See also: quaternary structure -- allosteryIn biochemistry, an enzyme or other protein is allosteric if its activity or efficiency changes in response to the binding of an effector molecule at a so-called allosteric site''. Changes that enhance activity are referred to as allosteric activation whi -- cooperativityIn biochemistry, a macromolecule has cooperative binding if when binding a ligand, the affinity of the ligand for the molecule changes depending on the amount of ligand already bound. A macromolecule is said to have positive cooperativity if the binding o

Protein structureProteins are amino acid chains, made up from 20 different L-α-amino acids, also referred to as residues, that fold into unique 3-dimensional protein structures . The shape into a which a protein naturally folds is known as its native state, which is

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Topics: Protein Subunit Multimeric Subunits Atp Gene Chain Catalytic...

Proteinmyoglobin, showing coloured alpha helices. This protein was the first to have its structure solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, which led to them receiving a Nobel Prize in Chemistry. A protein is a complex,	Protein biosynthesisnucleus of the cell light blue , genes (DNA, dark blue are transcribed into RNA. This RNA is then subject to post-transcriptional modification and control, resulting in a mature mRNA red that is then transported out of the nucleus and into the cytoplasm p	Protein kinaseA protein kinase is an enzyme that can transfer a phosphate group from a donor molecule (usually ATP) to an amino acid residue of a protein. The protein kinase mechanism is used in signal transduction for the regulation of enzymes: phosphorylation can act
Protein phosphataseProtein phosphatases are enzymes that remove phosphate groups that have been attached to amino acid residues of proteins by protein kinases. The phosphates are important in signal transduction by regulating the proteins they are attached to. To reverse th	Protein targetingProtein targeting includes the mechanisms by which a biological cell transports proteins to the appropriate organelle for insertion into a membrane or secretion to the outside. This article deals with protein targeting in eukaryotes except as noted. Prote	ProteinoidProteinoids are protein-like molecules formed inorganically from amino acids. Some theories of abiogenesis propose that proteinoids were a precursor to the first living cells. The inorganic polymerization of amino acids into proteins through the formation
Protein folding	Protein Data Bank	Proteinuria
Protein catabolism	Protein engineering	Protein sequencer
Protein (band)	Protein structure prediction	Protein subunit

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