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
Representatives:
e2v3zA2[A:1-176] nonrep Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL ; X-RAY DIFFRACTION 1.56Å
e2bwsA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE P ; ligands: CL ; X-RAY DIFFRACTION 1.750Å
e1a16A2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
AMINOPEPTIDASE P ; X-RAY DIFFRACTION 2.3Å
e1w7vC2[C:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL ; X-RAY DIFFRACTION 2.000Å
e2bhcA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; X-RAY DIFFRACTION 2.400Å
e1w2mF2[F:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL,IPA ; X-RAY DIFFRACTION 2.4Å
e2bwwA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
AMINOPEPTIDASE P ; X-RAY DIFFRACTION 2.600Å
e2v3xA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL ; X-RAY DIFFRACTION 1.70Å
e1w2mD2[D:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL,IPA ; X-RAY DIFFRACTION 2.4Å
e2bh3A2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: LEU,PRO,ZN ; X-RAY DIFFRACTION 2.400Å
e2bn7A2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; X-RAY DIFFRACTION 2.400Å
e1w7vD2[D:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL ; X-RAY DIFFRACTION 2.000Å
e1m35F2[F:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
AMINOPEPTIDASE P ; X-RAY DIFFRACTION 2.4Å
e1wlrA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro aminopeptidase ; ligands: CL,IPA ; X-RAY DIFFRACTION 2.10Å
e2bwtA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE P ; X-RAY DIFFRACTION 2.900Å
e1n51A2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; X-RAY DIFFRACTION 2.3Å
e1m35C2[C:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
AMINOPEPTIDASE P ; X-RAY DIFFRACTION 2.4Å
e1m35D2[D:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
AMINOPEPTIDASE P ; X-RAY DIFFRACTION 2.4Å
e1wbqB2[B:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL ; X-RAY DIFFRACTION 2.300Å
e2bhbA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: ZN ; X-RAY DIFFRACTION 2.40Å
e1wbqA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL ; X-RAY DIFFRACTION 2.300Å
e1wl9A2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro aminopeptidase ; ligands: CL ; X-RAY DIFFRACTION 1.90Å
e1m35A2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
AMINOPEPTIDASE P ; X-RAY DIFFRACTION 2.4Å
e1w2mE2[E:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL,IPA ; X-RAY DIFFRACTION 2.4Å
e2v3yA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL ; X-RAY DIFFRACTION 1.60Å
e1w2mB2[B:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL,IPA ; X-RAY DIFFRACTION 2.4Å
e1wl6A2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro aminopeptidase ; ligands: CL,IPA ; X-RAY DIFFRACTION 2.0Å
e2bhdA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; X-RAY DIFFRACTION 2.500Å
e2bhaA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; X-RAY DIFFRACTION 2.400Å
e2bwyA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
AMINOPEPTIDASE P ; X-RAY DIFFRACTION 2.400Å
e2bwvA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
AMINOPEPTIDASE P ; ligands: CL ; X-RAY DIFFRACTION 1.700Å
e1w7vB2[B:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL ; X-RAY DIFFRACTION 2.000Å
e1w2mC2[C:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL,IPA ; X-RAY DIFFRACTION 2.4Å
e1w7vA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL ; X-RAY DIFFRACTION 2.000Å
e2bwuA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
AMINOPEPTIDASE P ; X-RAY DIFFRACTION 2.200Å
e1jawA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
AMINOPEPTIDASE P ; X-RAY DIFFRACTION 2.7Å
e1m35B2[B:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
AMINOPEPTIDASE P ; X-RAY DIFFRACTION 2.4Å
e1wbqC2[C:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL ; X-RAY DIFFRACTION 2.300Å
e1m35E2[E:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
AMINOPEPTIDASE P ; X-RAY DIFFRACTION 2.4Å
e1w2mA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL,IPA ; X-RAY DIFFRACTION 2.4Å
e1wbqD2[D:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
XAA-PRO AMINOPEPTIDASE ; ligands: CL ; X-RAY DIFFRACTION 2.300Å
e3ig4A2[A:1-172] Image Pymol Jmol Links: PDB, SCOP, CATH
Xaa-pro aminopeptidase ; ligands: SO4 ; X-RAY DIFFRACTION 2.89Å
e3ig4B2[B:1-172] Image Pymol Jmol Links: PDB, SCOP, CATH
Xaa-pro aminopeptidase ; ligands: SO4 ; X-RAY DIFFRACTION 2.89Å
e3ig4C2[C:1-172] Image Pymol Jmol Links: PDB, SCOP, CATH
Xaa-pro aminopeptidase ; ligands: SO4 ; X-RAY DIFFRACTION 2.89Å
e3ig4D2[D:1-172] Image Pymol Jmol Links: PDB, SCOP, CATH
Xaa-pro aminopeptidase ; ligands: SO4 ; X-RAY DIFFRACTION 2.89Å
e3ig4E2[E:1-172] Image Pymol Jmol Links: PDB, SCOP, CATH
Xaa-pro aminopeptidase ; ligands: SO4 ; X-RAY DIFFRACTION 2.89Å
e3ig4F2[F:1-172] Image Pymol Jmol Links: PDB, SCOP, CATH
Xaa-pro aminopeptidase ; ligands: SO4 ; X-RAY DIFFRACTION 2.89Å
e2bwxA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
AMINOPEPTIDASE P ; ligands: CL ; X-RAY DIFFRACTION 1.700Å
e2oknB4[B:7-188] Image Pymol Jmol Links: PDB, SCOP, CATH
Xaa-Pro dipeptidase ; X-RAY DIFFRACTION 2.45Å
e2iw2B4[B:7-188] Image Pymol Jmol Links: PDB, SCOP, CATH
XAA-PRO DIPEPTIDASE ; X-RAY DIFFRACTION 1.82Å
e2iw2A4[A:7-188] Image Pymol Jmol Links: PDB, SCOP, CATH
XAA-PRO DIPEPTIDASE ; X-RAY DIFFRACTION 1.82Å
e2oknA4[A:7-188] Image Pymol Jmol Links: PDB, SCOP, CATH
Xaa-Pro dipeptidase ; X-RAY DIFFRACTION 2.45Å
e4pv4A2[A:1-174] Image Pymol Jmol Links: PDB, SCOP, CATH
Proline aminopeptidase P II ; ligands: EDO,P6G,PGE ; X-RAY DIFFRACTION 1.76Å
e4pv4B2[B:1-174] Image Pymol Jmol Links: PDB, SCOP, CATH
Proline aminopeptidase P II ; ligands: 1PE,EDO ; X-RAY DIFFRACTION 1.76Å
e5x49A1[A:57-247] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Probable Xaa-Pro aminopeptidase 3 ; ligands: 01B,12P,DMS,EDO ; X-RAY DIFFRACTION 1.65Å
e5x49B1[B:57-247] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Probable Xaa-Pro aminopeptidase 3 ; ligands: 01B,12P,DMS,EDO ; X-RAY DIFFRACTION 1.65Å
e5m4gA2[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GOL ; X-RAY DIFFRACTION 1.480Å
e5m4gB2[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GOL ; X-RAY DIFFRACTION 1.480Å
e5m4jA2[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION
e5m4jB1[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION
e5m4lA2[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GOL,LEU,PRO ; X-RAY DIFFRACTION 1.490Å
e5m4lB2[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GOL,LEU,PRO ; X-RAY DIFFRACTION 1.490Å
e5m4qA2[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GOL,PRO ; X-RAY DIFFRACTION 1.728Å
e5m4qB1[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GOL,PRO ; X-RAY DIFFRACTION 1.728Å
e5wzeB2[B:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Aminopeptidase P ; ligands: ALA,EDO,GOL,NA,PRO ; X-RAY DIFFRACTION 1.783Å
e5mbyA2[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.549Å
e5mc0A2[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.558Å
e5mbzB2[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.499Å
e5mc0B1[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.558Å
e5mc2A2[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.698Å
e5mc2B1[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.698Å
e5mc4A1[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.799Å
e5mc4B1[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.799Å
e5mc5B2[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.899Å
e5mbzA1[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.499Å
e5mc1A2[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.428Å
e5mc1B2[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.428Å
e5mc3A2[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.518Å
e5mc3B2[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.518Å
e5mc5A2[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.899Å
e5wzeA2[A:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Aminopeptidase P ; ligands: ALA,CA,GOL,NA,PRO,SO4 ; X-RAY DIFFRACTION 1.783Å
e5wzeC1[C:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Aminopeptidase P ; ligands: ALA,CA,GOL,PRO ; X-RAY DIFFRACTION 1.783Å
e5wzeD2[D:1-176] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Aminopeptidase P ; ligands: ALA,EDO,GOL,PRO,SO4 ; X-RAY DIFFRACTION 1.783Å
e5mbyB2[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.549Å
e6h2qA1[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GOL,LEU,PRO ; X-RAY DIFFRACTION 1.78Å
e6h2pB2[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GOL ; X-RAY DIFFRACTION 1.479Å
e6h2qB1[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GOL,LEU,PRO ; X-RAY DIFFRACTION 1.78Å
e6h2pA1[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GOL ; X-RAY DIFFRACTION 1.479Å
e6a9tA1[A:58-245] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Intermediate cleaving peptidase 55 ; X-RAY DIFFRACTION 2.15Å
e6a9uA1[A:59-245] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Intermediate cleaving peptidase 55 ; X-RAY DIFFRACTION 2.40Å
e6a9vA2[A:59-245] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Intermediate cleaving peptidase 55 ; X-RAY DIFFRACTION 2.90Å
e6qsbB2[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GOL ; X-RAY DIFFRACTION 1.99Å
e6qsbA2[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GOL ; X-RAY DIFFRACTION 1.99Å
e6qscA2[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.5690Å
e6qscB1[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.5690Å
e6sreB2[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.39Å
e6srfB2[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,PRO ; X-RAY DIFFRACTION 1.8470Å
e6srfA2[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.8470Å
e6srgA1[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; X-RAY DIFFRACTION 2.5580Å
e6srgB2[B:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 2.5580Å
e6sreA2[A:6-187] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Xaa-Pro dipeptidase ; ligands: GLY,GOL,PRO ; X-RAY DIFFRACTION 1.39Å
Pseudo group of domains that do not map to PFam family profiles. Domains inside should not be considered as in one family.
few secondary structure elementsstabilized by cofactors or disulfides
extended segmentsextended, non-globular segments, frequently bind to other proteins to form complexes