Aminoacyl-tRNA synthetases, class II is a family of

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

s. These proteins

catalyse Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

the attachment of an

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

to its cognate

transfer RNA Transfer RNA (abbreviated tRNA and formerly referred to as sRNA, for soluble RNA) is an adaptor molecule composed of RNA, typically 76 to 90 nucleotides in length (in eukaryotes), that serves as the physical link between the mRNA and the amino ac ...

molecule in a highly specific two-step reaction. These proteins differ widely in size and oligomeric state, and have a limited

sequence homology Sequence homology is the biological homology between DNA, RNA, or protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments of DNA can have shared ancestry because of three phenomena: either a spe ...

. The 20 aminoacyl-tRNA synthetases are divided into two classes, I and II. Class I aminoacyl-tRNA synthetases contain a characteristic Rossman fold catalytic domain and are mostly monomeric. Class II aminoacyl-tRNA synthetases share an anti-parallel beta-sheet fold flanked by alpha-helices, and are mostly dimeric or multimeric, containing at least three conserved regions. However, tRNA binding involves an alpha-helical structure that is conserved between class I and class II synthetases. In reactions catalysed by the class I aminoacyl-tRNA synthetases, the aminoacyl group is coupled to the 2'-hydroxyl of the tRNA, while, in class II reactions, the 3'-hydroxyl site is preferred. The synthetases specific for arginine, cysteine, glutamic acid, glutamine, isoleucine, leucine, methionine, tyrosine, tryptophan and valine belong to class I synthetases; these synthetases are further divided into three subclasses, a, b and c, according to sequence homology. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, lysine, phenylalanine, proline, serine, and threonine belong to class-II synthetases.

Human proteins containing this domain

DARS DARS may refer to: * DARS (gene), a human gene * DARS (radar) Deployable Air operations centre, Recognized air picture production centre, Sensor Fusion Post, a NATO mobile deployable Command & Control radar system * DoD Architecture Registry Syst ...

DARS2 DARS may refer to: * DARS (gene), a human gene * DARS (radar) Deployable Air operations centre, Recognized air picture production centre, Sensor Fusion Post, a NATO mobile deployable Command & Control radar system * DoD Architecture Registry Syst ...

KARS Kars (; ku, Qers; ) is a city in northeast Turkey and the capital of Kars Province. Its population is 73,836 in 2011. Kars was in the ancient region known as ''Chorzene'', (in Greek Χορζηνή) in classical historiography ( Strabo), part of ...

* NARS *

NARS2 Nars or NARS may refer to: *Karl Nars (1874–1952), Finnish industrialist * Natural Area Reserves System such as the Natural Area Reserves System Hawaii * North Atlantic Radio System, a troposcatter communications system for the air defence of NATO ...

References

{{DEFAULTSORT:Aminoacyl Trna Synthetases, Class Ii Protein families EC 3.1.1