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Table 1 Secondary structure features of major β-GF structural categories.

From: Small but versatile: the extraordinary functional and structural diversity of the β-grasp fold

Higher-order Classification Lineage Name Secondary Structural Features Common to the β-GF Fold1
   S1 L1 S2 L2 H L3/LS S3 L4 S4 L5/CA S5 tail notes
Basal 4-stranded versions of the β-GF IF3-N S1 -- S2 -- H -- S3 -- O O S5 --  
  Archeo-eukaryotic RNA poly. β-subunit S1 -- S2 -- H -- S3 -- O O S5 --  
Sporadically-distributed 4-stranded versions Yml108w S1 cc S2 -- H -- S3 -- O O S5 h  
  BofC S1 -- S2 -- H -- S3 -- O O S5 --  
  Immunoglobulin-binding S1 -- S2 -- H -- S3 -- O O S5 --  
  POZ S1 -- S2 -- H h S3 -- O O S5 --  
Nudix superfamily Nudix (MutT) S1 -- S(ee)2 -- H * S3 -- O O S5 e  
Fasciclin-like assemblage L25 S1 -- S2 -- H ee* S3 -- O O S5 -- 3
  glutamine synthetase N-terminal S1 -- S2 -- H eee* S3 -- O O S5 -- 3
  fasciclin S1 hhh S2 -- H ee* S3 -- O O S5 -- 3
  phosphoribosyl AMP cyclohydrolase (HisI) S1 -- S2 -- H ee* S3 -- O O S5 -- 3,4
5-stranded assemblage: classical 5-stranded clade MoaD S1 H S2 -- H h** S3 -- S4 * S5 --  
  ThiS S1 -- S2 -- H * S3 -- S4 * S5 --  
  TmoB S1 -- S2 -- H * S3 -- S4 * S5 --  
  Superantigen S1 -- S2 -- H * S3 -- S4 h* S5 --  
  Strepto/Staphylokinase S1 -- S2 -- H * S3 -- S4 * S5 --  
  YukD S1 -- S2 -- H * S3 -- S4 * S5 --  
  TGS S1 -- S2 -- H h* S3 -- S4 * S5 --  
  Aldehyde OR2 N-terminal domain S1 -- S2 -- H * S3 -- S4 eh* S5 --  
5-stranded assemblage: Selected eukaryote UB-like superfamily members classic UB-like S1 -- S2 -- H * S3 -- S4 * S5 --  
  PB1 S1 -- S2 -- H * S3 -- S4 h* S5 --  
  CAD/Doublecortin (DCX) S1 -- S2 -- H * S3 -- S4 [h]* S5 -- 6
  RA S1 -- S2 -- H * S3 -- S4 h* S5 --  
  Elongin S1 -- S2 -- H * S3 -- S4 * S5 --  
  UBX S1 -- S2 -- H * S3 -- S4 * S5 --  
  E1/UFD O -- S2 -- H * S3 -- S4 * S5 S6 7
5-stranded assemblage: soluble ligand binding or metal ion chelating clade molydopterin-dependent oxidoreductase S1 -- S2 hehee H * S3 -- S4 eee* S5 --  
  SLBB: Nqo1-type S1 -- S2 -- H * S3 -- S4 hh* S5 -- 5
  SLBB: transcobalamin-type S1 -- S2 -- H eee* S3 -- S4 * S5 --  
  2Fe-2S ferredoxin S1 -- S2 -- H cc* S3 -- S4 * S5 --  
  L-proline DH-like OR2 N-terminal domain S1 -- S2 -- H ee* S3 -- S4 * S5 --  
Miscellaneous WWE S1 -- S2 -- H e* S3 -- O O S5 e 8
  FimD N-terminal S1 -- S2 ee H * S3 -- O O S5 --  
  S4 O O O O H h* S3 -- S4 * S5 --  
  1. 1. S: Strand, L: Loop, H: Helix, LS: Lateral Shelf, CA: Connector Arm, O: absence of given feature, --: presence of a loop feature, *: presence of LS or CA, h: insert in helical conformation, e: insert in extended conformation (strand-like), cc: long coil insert.
  2. 2. OR: oxidoreductase.
  3. 3. Versions form barrel through insertion of strands at the lateral shelf.
  4. 4. Barrel is less pronounced in this version, strands are inserted more upstream relative to the other 3 versions.
  5. 5. Two small helices are present in ascending arm.
  6. 6. Single helix found at ascending arm in several members.
  7. 7. Circular permutation results in new connections between strands; the S1 strand is found at C-terminus (See Figures 1, 2).
  8. 8. Additional strand at tail inserted between S1 and S5; lateral shelf forms strand that also stacks with central sheet.