>TIGR00470 sepS O-phosphoseryl-tRNA(Cys) synthetase; InterPro: IPR005246 The aminoacyl-tRNA synthetases (6.1.1. from EC) catalyse the attachment of an amino acid to its cognate transfer RNA molecule in a highly specific two-step reaction. These proteins differ widely in size and oligomeric state, and have limited sequence homology . 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 . All known phenylalanyl-tRNA synthetases, excepting a monomeric mitochondrial form, have an alpha 2 beta 2 heterotetrameric structure. This family of archaeal proteins resembles known phenylalanyl-tRNA synthetase alpha chains but is longer and of unknown function; more generally, it resembles class 2 aminoacyl tRNA ligases. .

Probab=92.29  E-value=0.064  Score=31.57  Aligned_cols=34  Identities=35%  Similarity=0.826  Sum_probs=25.0

Q ss_pred             HCCCC-CCCCEECCHHHHHHHHCCCCCCEECCCCCC
Q ss_conf             60869-846132468999899826288404127867
Q gi|254781118|r  457 TYGMP-PASGLGLGIDRLIMLLTNAPSIRDVILFPA  491 (502)
Q Consensus       457 ~yG~P-PhgG~glGldRL~m~l~g~~~IRdvi~FP~  491 (502)
T Consensus       328 ~Y~Id~pVMNLGlGVERlAMIlygy~DVR~MV-YPQ  362 (558)
T TIGR00470       328 KYDIDVPVMNLGLGVERLAMILYGYEDVRKMV-YPQ  362 (558)
T ss_pred             HCCCCCCEEECCCHHHHHHHHHHCHHHHHHCC-CCC
T ss_conf             16849652225631876787781403343226-884