TABLE 1.

Structural classification of aminoacyl-tRNA synthetase (49)

CharacteristicClass IClass II
Conserved characteristics
    Active site structureRossman foldAntiparallel β-sheet
    MotifsHIGH, KMSKSMotif 1, Motif 2, Motif 3
    ATP conformationExtendedBent
Enzyme subclassSubclass Ia [subunit structure(s)]Subclass IIa [subunit structure(s)]
    IleRS (α)    Ala-RS (α, α4)
    LeuRS (α)    ProRS (α2)
    ValRS (α)    HisRS (α2)
    CysRS (α)    SerRS (α2)
    MetRS (α, α2)    ThrRS (α2)
    ArgRS (α)    GlyRS (α2, α2β2)
Subclass Ib (subunit structure)Subclass IIb (subunit structure)
    GlnRS (α)    AsnRS (α2)
    GluRS (α)    AspRS (α2)
    LysRS-I (α)    LysRS-II (α2)
Subclass Ic (subunit structure)Subclass IIc (subunit structure)
    TyrRS (α2)    Phe-RS (α2β2)
    TrpRS (α2)