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
![](/ecod/img/m.gif)
![](/ecod/img/m.gif)
![](/ecod/img/m.gif)
![](/ecod/img/m.gif)
Representatives:
e1twfB3[B:851-974]
nonrep
Image
Pymol
Jmol Links:
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SCOP,
CATH, PubMed,
DOI
DNA-DIRECTED RNA POLYMERASE II 140 KDA POLYPEPTIDE ; X-RAY DIFFRACTION 2.3Å
e1smyC9[C:701-833]
nonrep
Image
Pymol
Jmol Links:
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SCOP,
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DOI
DNA-DIRECTED RNA POLYMERASE BETA CHAIN ; ligands: MG ; X-RAY DIFFRACTION 2.7Å
e4c2mB6[B:799-911]
nonrep
Image
Pymol
Jmol Links:
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DOI
DNA-DIRECTED RNA POLYMERASE I SUBUNIT RPA135 ; X-RAY DIFFRACTION 2.80Å
e4by7B6[B:851-974]
nonrep
Image
Pymol
Jmol Links:
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DOI
DNA-DIRECTED RNA POLYMERASE II SUBUNIT RPB2 ; X-RAY DIFFRACTION 3.15Å
e5ip7B1[B:851-974] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase II subunit RPB2 ; X-RAY DIFFRACTION 3.520Å
e5ip9B7[B:851-974] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase II subunit RPB2 ; X-RAY DIFFRACTION 3.450Å
e2e2hB5[B:851-974] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-DIRECTED RNA POLYMERASE II 140 KDA POLYPEPTIDE ; X-RAY DIFFRACTION 3.95Å
e2nvzB5[B:851-974] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase II 140 kDa polypeptide ; X-RAY DIFFRACTION 4.2Å
e2pmzB6[B:750-872] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit B ; X-RAY DIFFRACTION 3.400Å
e2pmzR7[R:750-872] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit B ; X-RAY DIFFRACTION 3.400Å
e4b1oB7[B:753-875] Image Pymol Jmol Links: PDB, SCOP, CATH Obsolete PDB
e4aybB4[B:753-875] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-DIRECTED RNA POLYMERASE ; ligands: ZN ; X-RAY DIFFRACTION 3.20Å
e3hkzJ3[J:750-872] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit B ; X-RAY DIFFRACTION 3.4Å
e3hkzB1[B:750-872] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit B ; X-RAY DIFFRACTION 3.4Å
e4v8sAR1[AR:753-875] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-DIRECTED RNA POLYMERASE ; X-RAY DIFFRACTION 4.30Å
e4v8sBB2[BB:753-875] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-DIRECTED RNA POLYMERASE ; X-RAY DIFFRACTION 4.30Å
e4b1pR7[R:753-875] Image Pymol Jmol Links: PDB, SCOP, CATH Obsolete PDB
e3h0gN2[N:840-963] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase II subunit RPB2 ; X-RAY DIFFRACTION 3.650Å
e3h0gB5[B:840-963] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase II subunit RPB2 ; X-RAY DIFFRACTION 3.650Å
e2y0sB5[B:753-875] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-DIRECTED RNA POLYMERASE ; X-RAY DIFFRACTION 3.79Å
e2wb1R7[R:753-875] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-DIRECTED RNA POLYMERASE RPO2 SUBUNIT ; X-RAY DIFFRACTION 3.52Å
e2wb1B2[B:753-875] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-DIRECTED RNA POLYMERASE RPO2 SUBUNIT ; X-RAY DIFFRACTION 3.52Å
e2waqB5[B:753-875] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-DIRECTED RNA POLYMERASE RPO2 SUBUNIT ; X-RAY DIFFRACTION 3.35Å
e7okxB7[B:883-1006] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit beta ; ELECTRON MICROSCOPY
e7ok0B7[B:748-870] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit B ; ELECTRON MICROSCOPY
e7okyB7[B:883-1006] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit beta ; ELECTRON MICROSCOPY
e7ol0B7[B:883-1006] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit beta ; ELECTRON MICROSCOPY
e7oq4B7[B:748-870] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit B ; ELECTRON MICROSCOPY
e7fjiB7[B:767-891] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase III subunit RPC2 ; ELECTRON MICROSCOPY
e7oo3B7[B:806-929] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit beta ; ELECTRON MICROSCOPY
e7opdB7[B:806-929] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit beta ; ELECTRON MICROSCOPY
e7oznB6[B:806-929] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit beta ; ELECTRON MICROSCOPY
e7oznN6[N:806-929] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit beta ; ELECTRON MICROSCOPY
e7ozoB6[B:806-929] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit beta ; ELECTRON MICROSCOPY
e7ozoN6[N:806-929] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit beta ; ELECTRON MICROSCOPY
e7ozpB6[B:806-929] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit beta ; ELECTRON MICROSCOPY
e7pksB7[B:806-929] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
DNA-directed RNA polymerase subunit beta ; ELECTRON MICROSCOPY
e2e2iB9[B:851-974]
nonrep
Image
Pymol
Jmol Links:
PDB,
SCOP,
CATH, PubMed,
DOI
DNA-DIRECTED RNA POLYMERASE II 140 KDA POLYPEPTIDE ; X-RAY DIFFRACTION 3.41Å
e4kmuC5[C:713-790]
nonrep
Image
Pymol
Jmol Links:
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SCOP,
CATH, PubMed,
DOI
DNA-DIRECTED RNA POLYMERASE SUBUNIT BETA ; X-RAY DIFFRACTION 3.85Å
e4kmuC6[C:828-938,C:1045-1062]
nonrep
Image
Pymol
Jmol Links:
PDB,
SCOP,
CATH, PubMed,
DOI
DNA-DIRECTED RNA POLYMERASE SUBUNIT BETA ; X-RAY DIFFRACTION 3.85Å
![](/ecod/img/p.gif)
Pseudo group of domains that do not map to PFam family profiles. Domains inside should not be considered as in one family.
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