Evolutionary classification of protein domain structures
alpha arraysalpha-helix arrays with mainly perpendicular helices
X: HhH/H2TH
H: SAM/DNA-glycosylase
T: PAP/OAS1 substrate-binding domain
the fourth helix changed to strands
F: Unmapped domains
Pseudo group of domains that do not map to PFam family profiles. Domains inside should not be considered as in one family.
Representatives:
e6e0oA2[A:184-292]
* 
nonrep
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cGAS/DncV-like nucleotidyltransferase in E. coli homolog ; X-RAY DIFFRACTION 1.25Å
e6e0kA2[A:181-296]
* nonrep
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Pymol
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cGAS/DncV-like nucleotidyltransferase in E. coli homolog ; X-RAY DIFFRACTION 1.60Å
e7x4cA2[A:189-307]
* nonrep
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Pymol
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EfCdnE ; ligands: TLA ; X-RAY DIFFRACTION 1.75Å
e6p82A1[A:169-300]
* nonrep
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Pymol
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SCOP,
CATH, PubMed,
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Nucleotidyltransferase ; ligands: SO4 ; X-RAY DIFFRACTION 2.05Å
alpha bundlesalpha-helix bundles with mainly parallel helices
alpha superhelicesrepeating alpha-helix hairpins form a superhelix
alpha duplicates or obligate multimersalpha duplicates or monomers associate together to form a compact domain
alpha complex topologyalpha domain with complex and unique topology that cannot be described as array or bundle or superhelix
beta barrelssingle beta-sheet folded upon itself to form a barrel
beta meanderssingle beta-sheet with mainly meander topology
beta sandwichestwo beta-sheets stacked together to form a sandwich
beta duplicates or obligate multimersbeta duplicates or monomers associate together to form a compact domain
beta complex topologybeta domains with complex and unique topology that cannot be described as barrel or sandwich or meander
a+b two layersone alpha-helix layer and one beta-sheet layer
a+b three layersone mainly antiparallel beta-sheet layer sandwiched between two alpha-helix layers
a+b four layerstwo beta-sheet layers sandwiched between two alpha-helix layers
a+b complex topologyalpha and beta domain with complex and unique topology that cannot be described in layers
a+b duplicates or obligate multimersalpha and beta duplicates or monomers associated together to form a compact domain
a/b barrelsrepeating beta-alpha units form a barrel
a/b three-layered sandwichesrepeating beta-alpha units form a sandwich with a mainly parallel beta-sheet layer stacked between two alpha-helix layers
mixed a+b and a/balpha and beta domain consists of both a+b and a/b regions
few secondary structure elementsstabilized by cofactors or disulfides
extended segmentsextended, non-globular segments, frequently bind to other proteins to form complexes