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

Refs: Structure 14, 1489-1498; Current opinion in structural biology 18, 358-365


126354, 3-crossover-4

Representatives:
e1oewA2[A:1-177]
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ENDOTHIAPEPSIN ; ligands: SER,SO4,THR ; X-RAY DIFFRACTION 0.91Å
e1oewA3[A:178-329]
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ENDOTHIAPEPSIN ; ligands: GOL,SER,SO4,THR ; X-RAY DIFFRACTION 0.91Å
e1wkrA2[A:1-169]
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POLYPOROPEPSIN ; ligands: SO4 ; X-RAY DIFFRACTION 1.3Å
e1wkrA3[A:170-340]
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POLYPOROPEPSIN ; ligands: SO4 ; X-RAY DIFFRACTION 1.3Å
e2qp8A2[A:245-447]
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Beta-secretase 1 ; ligands: SC7 ; X-RAY DIFFRACTION 1.500Å
e2qp8A3[A:58-244]
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Beta-secretase 1 ; ligands: SC7,TAR ; X-RAY DIFFRACTION 1.500Å
e2bjuA2[A:1-177]
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PLASMEPSIN II ; ligands: IH4 ; X-RAY DIFFRACTION 1.56Å
e2bjuA3[A:178-329]
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PLASMEPSIN II ; ligands: IH4 ; X-RAY DIFFRACTION 1.56Å
e1dpjA2[A:0-147]
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PROTEINASE A ; ligands: NAG ; X-RAY DIFFRACTION 1.78Å
e1dpjA3[A:148-326]
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PROTEINASE A ; ligands: NAG,SO4 ; X-RAY DIFFRACTION 1.78Å
e1j71A1[A:1-179]
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Aspartic proteinase ; ligands: EOH ; X-RAY DIFFRACTION 1.8Å
e1j71A2[A:180-334]
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Aspartic proteinase ; ligands: EOH ; X-RAY DIFFRACTION 1.8Å
e3qvcA1[A:77P-328]
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HISTO-ASPARTIC PROTEASE ; ligands: EDO ; X-RAY DIFFRACTION 2.1Å
e1lyw.1[A:3-97,B:106-346] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
CATHEPSIN D ; ligands: EPE ; X-RAY DIFFRACTION 2.5Å
e1lya.1[C:1-97,D:106-346] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
CATHEPSIN D ; ligands: NAG ; X-RAY DIFFRACTION
e1lyb.1[C:1-97,D:106-346] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
CATHEPSIN D ; ligands: NAG ; X-RAY DIFFRACTION
e1lyw.2[G:3-97,H:106-346] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
CATHEPSIN D ; ligands: EPE ; X-RAY DIFFRACTION 2.5Å
e1lyb.2[A:1-97,B:106-346] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
CATHEPSIN D ; ligands: NAG ; X-RAY DIFFRACTION
e1lya.2[A:1-97,B:106-346] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
CATHEPSIN D ; ligands: NAG ; X-RAY DIFFRACTION
e1lyw.3[E:3-97,F:106-346] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
CATHEPSIN D ; ligands: EPE ; X-RAY DIFFRACTION 2.5Å
e1lyw.4[C:3-97,D:106-346] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
CATHEPSIN D ; ligands: EPE ; X-RAY DIFFRACTION 2.5Å
e1miqA2[A:78P-327] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
plasmepsin ; X-RAY DIFFRACTION 2.5Å
e1miqB2[B:76P-327] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
plasmepsin ; X-RAY DIFFRACTION 2.5Å
e1pfzD2[D:79P-329] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
PROPLASMEPSIN II ; ligands: GOL ; X-RAY DIFFRACTION 1.85Å
e1pfzB2[B:78P-328] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
PROPLASMEPSIN II ; X-RAY DIFFRACTION 1.85Å
e1pfzA2[A:79P-329] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
PROPLASMEPSIN II ; ligands: GOL ; X-RAY DIFFRACTION 1.85Å
e1pfzC2[C:78P-329] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
PROPLASMEPSIN II ; ligands: GOL ; X-RAY DIFFRACTION 1.85Å
e1qrpE2[E:148-326] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
PEPSIN 3A ; ligands: HH0 ; X-RAY DIFFRACTION 1.96Å
e1psoE2[E:148-326] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed,
PEPSIN 3A ; X-RAY DIFFRACTION 2.0Å
e1psnA2[A:148-326] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed,
PEPSIN 3A ; X-RAY DIFFRACTION 2.2Å
e3utlA2[A:148-326] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Pepsin A ; X-RAY DIFFRACTION 2.6Å
e1flhA2[A:148-326] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
UROPEPSIN ; X-RAY DIFFRACTION 2.45Å
e4oc6B1[B:106-348] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Cathepsin D heavy chain ; ligands: 2S1,GOL,NAG ; X-RAY DIFFRACTION 2.64Å
e4obzB1[B:107-346] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Cathepsin D heavy chain ; ligands: 2S4,NAG ; X-RAY DIFFRACTION 2.90Å
e4od9B1[B:107-346] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Cathepsin D heavy chain ; ligands: 2RZ,ACT,NAG ; X-RAY DIFFRACTION 1.9Å
e4od9D1[D:106-346] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Cathepsin D heavy chain ; ligands: 2RZ,ACT,NAG ; X-RAY DIFFRACTION 1.9Å
e4y6mA1[A:1-329] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Plasmepsin-2 ; ligands: 48Q,GOL ; X-RAY DIFFRACTION 2.27Å
e4y6mC1[C:1-329] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Plasmepsin-2 ; ligands: 48Q,GOL ; X-RAY DIFFRACTION 2.27Å
e4y6mB1[B:2-329] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Plasmepsin-2 ; ligands: 48Q,GOL ; X-RAY DIFFRACTION 2.27Å
e4ya8D1[D:2-329] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Plasmepsin-2 ; ligands: 49W ; X-RAY DIFFRACTION 3.301Å
e5bwyA1[A:78P-329] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Plasmepsin-2 ; X-RAY DIFFRACTION 2.64Å
e5yiaA1[A:4-331] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Plasmepsin II ; ligands: 8V9,CPS,GOL,PO4 ; X-RAY DIFFRACTION 2.0Å
e5yibA1[A:4-331] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Plasmepsin II ; ligands: 8VC,CPS,EDO,GOL ; X-RAY DIFFRACTION 2.15Å
e5yicA1[A:4-331] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Plasmepsin II ; ligands: 8VO,CPS,GOL ; X-RAY DIFFRACTION 1.9Å
e5yidA1[A:5-331] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Plasmepsin II ; ligands: CPS,K95,NA ; X-RAY DIFFRACTION 2.1Å
e5yieA1[A:5-331] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Plasmepsin II ; ligands: 8VF,CPS,NA ; X-RAY DIFFRACTION 2.1Å
e6qbgB1[B:107-347] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Cathepsin D ; ligands: DMS,HVT,NAG,SO4 ; X-RAY DIFFRACTION 1.800Å
e6qbhB1[B:107-347] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Cathepsin D ; ligands: DMS,NAG,S43,SO4 ; X-RAY DIFFRACTION 1.85Å
e6qcbB1[B:107-347] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Cathepsin D ; ligands: DMS,HWE,NAG,PO3,SO4 ; X-RAY DIFFRACTION 1.55Å
e6kubA1[A:-4-328] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
HAP protein ; ligands: GOL,PEG ; X-RAY DIFFRACTION 2.0Å
e6kucA1[A:-1-328] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
HAP protein ; ligands: GOL,PEG ; X-RAY DIFFRACTION 2.5Å
e6kudA1[A:-1-328] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
HAP protein ; ligands: GOL ; X-RAY DIFFRACTION 2.9Å
e7ve0B1[B:4-329] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Plasmepsin II ; ligands: CPS,EDO,RIT ; X-RAY DIFFRACTION 1.9Å
e7ve0A1[A:3-331] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Plasmepsin II ; ligands: CPS,EDO,RIT ; X-RAY DIFFRACTION 1.9Å
e7ve2A1[A:3-331] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Plasmepsin II ; ligands: AB1,CPS ; X-RAY DIFFRACTION 3.2Å
e4zl4A2[A:273-470]
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Aspartic protease PM5 ; ligands: 4PK,EDO,SO4 ; X-RAY DIFFRACTION 2.37Å
e4obz.1[C:-4-98,D:106-346]
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Cathepsin D heavy chain & Cathepsin D light chain ; ligands: NAG ; X-RAY DIFFRACTION 2.90Å
e1mppA1[A:-1-174]
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PEPSIN ; ligands: SO4 ; X-RAY DIFFRACTION
e1mppA2[A:175-332]
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PEPSIN ; X-RAY DIFFRACTION
e1smrA2[A:-2-174]
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RENIN ; X-RAY DIFFRACTION
e1smrA3[A:175-326]
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RENIN ; X-RAY DIFFRACTION

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