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
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
X: Thyroglobulin type-1 domain
H: Thyroglobulin type-1 domain
T: Thyroglobulin type-1 domain
F: Thyroglobulin_1
Representatives:
e4mzvA2[A:63-139]
nonrep
Image
Pymol
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Epithelial cell adhesion molecule ; X-RAY DIFFRACTION 1.86Å
e1icfI1[I:194-258]
nonrep
Image
Pymol
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DOI
PROTEIN (INVARIANT CHAIN) ; ligands: NAG ; X-RAY DIFFRACTION 2.0Å
e2dsrG1[G:151-229]
nonrep
Image
Pymol
Jmol Links:
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CATH, PubMed,
DOI
INSULIN-LIKE GROWTH FACTOR-BINDING PROTEIN 4 ; X-RAY DIFFRACTION 2.1Å
X: RING/U-box-like
binds two zincs. one in the same way as rubredoxin, probably related to rubredoxin. the other in a similar way as glucocorticoid receptor
extended segmentsextended, non-globular segments, frequently bind to other proteins to form complexes