Evolutionary classification of protein domain structures
alpha arraysalpha-helix arrays with mainly perpendicular helices
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
X: cradle loop barrel
Refs: Structure 14, 1489-1498; Current opinion in structural biology 18, 358-365
X: OB-fold
H: Nucleic acid-binding proteins
T: Nucleic acid-binding proteins
54123, 3-crossover-4
F: S1
Representatives:
e1go3E1[E:79-184]
nonrep
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DNA-DIRECTED RNA POLYMERASE SUBUNIT E ; X-RAY DIFFRACTION 1.750Å
e1luzA1[A:4-88]
nonrep
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PROTEIN K3 ; X-RAY DIFFRACTION 1.8Å
e1kl9A1[A:3-88]
nonrep
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EUKARYOTIC TRANSLATION INITIATION FACTOR 2 SUBUNIT 1 ; ligands: ZN ; X-RAY DIFFRACTION 1.90Å
e1hh2P1[P:127-198]
nonrep
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N UTILIZATION SUBSTANCE PROTEIN A ; X-RAY DIFFRACTION 2.1Å
e3bzkA1[A:637-730]
nonrep
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Tex ; X-RAY DIFFRACTION 2.30Å
e4nnhB1[B:278-445]
nonrep
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30S ribosomal protein S1 ; X-RAY DIFFRACTION 2.30Å
e2ix0A3[A:558-644]
nonrep
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EXORIBONUCLEASE 2 ; X-RAY DIFFRACTION 2.440Å
e2bx2L1[L:35-118]
nonrep
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RIBONUCLEASE E ; X-RAY DIFFRACTION 2.85Å
e2ahoB1[B:1-84]
nonrep
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Translation initiation factor 2 alpha subunit ; X-RAY DIFFRACTION 3.0Å
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.
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