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




Representatives:
e1qynA1[A:9-142]
nonrep
Image
Pymol
Jmol Links:
PDB,
SCOP,
CATH, PubMed,
DOI
Protein-export protein secB ; X-RAY DIFFRACTION 2.35Å
e5mtwB1[B:6-163] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SecB-like chaperone Rv1957 ; ligands: CA,DMS ; X-RAY DIFFRACTION 1.835Å
e5mtwC2[C:13-166] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SecB-like chaperone Rv1957 ; ligands: DMS ; X-RAY DIFFRACTION 1.835Å
e5mtwD2[D:10-162] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SecB-like chaperone Rv1957 ; ligands: CA ; X-RAY DIFFRACTION 1.835Å
e5mtwA2[A:9-163] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SecB-like chaperone Rv1957 ; ligands: CA ; X-RAY DIFFRACTION 1.835Å
e1fx3D1[D:17-151] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
PROTEIN-EXPORT PROTEIN SECB ; X-RAY DIFFRACTION 2.5Å
e1ozbG1[G:16-151] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein secB ; X-RAY DIFFRACTION 2.8Å
e1ozbD1[D:17-151] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein secB ; X-RAY DIFFRACTION 2.8Å
e1ozbB1[B:16-151] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein secB ; X-RAY DIFFRACTION 2.8Å
e1qynD1[D:9-142] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein secB ; X-RAY DIFFRACTION 2.35Å
e1qynC1[C:9-140] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein secB ; X-RAY DIFFRACTION 2.35Å
e1fx3A1[A:16-151] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
PROTEIN-EXPORT PROTEIN SECB ; X-RAY DIFFRACTION 2.5Å
e1ozbF1[F:16-151] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein secB ; X-RAY DIFFRACTION 2.8Å
e1ozbE1[E:16-151] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein secB ; X-RAY DIFFRACTION 2.8Å
e1fx3C1[C:16-151] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
PROTEIN-EXPORT PROTEIN SECB ; X-RAY DIFFRACTION 2.5Å
e1ozbC1[C:16-151] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein secB ; X-RAY DIFFRACTION 2.8Å
e1ozbH1[H:16-151] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein secB ; X-RAY DIFFRACTION 2.8Å
e1fx3B1[B:16-151] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
PROTEIN-EXPORT PROTEIN SECB ; X-RAY DIFFRACTION 2.5Å
e1qynB1[B:9-141] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein secB ; X-RAY DIFFRACTION 2.35Å
e1ozbA1[A:16-151] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein secB ; X-RAY DIFFRACTION 2.8Å
e5jtlA1[A:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtlB1[B:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtlC1[C:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtlD1[D:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtmA1[A:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtmB1[B:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtmC1[C:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtmD1[D:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtnA1[A:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtnB1[B:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtnC1[C:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtnD1[D:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtoA1[A:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtoB1[B:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtoC1[C:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtoD1[D:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtpA1[A:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtpB1[B:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtpC1[C:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtpD1[D:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtqA1[A:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtqB1[B:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtqC1[C:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtqD1[D:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtrA1[A:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtrB1[B:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtrC1[C:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR
e5jtrD1[D:1-155] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Protein-export protein SecB ; SOLUTION NMR

Pseudo group of domains that do not map to PFam family profiles. Domains inside should not be considered as in one family.
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