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X - Possible homology level

H - Homology level

T - Topology level

F - Family level

* - Provisional representative


Keyword search


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

X: Glycosyl hydrolase domain-like

some similarity with Ig fold

X: gp9 N-terminal domain-like
H: gp9 N-terminal domain-related
T: gp9 N-terminal domain-related
F: T4_gp9_10

PF07880 CL0187

Representatives:

e1qexA2[A:1-168] nonrep Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

PROTEIN (BACTERIOPHAGE T4 GENE PRODUCT 9 (GP9)) ; X-RAY DIFFRACTION 2.3Å

e1qexB1[B:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

PROTEIN (BACTERIOPHAGE T4 GENE PRODUCT 9 (GP9)) ; X-RAY DIFFRACTION 2.3Å

e1s2eA1[A:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; X-RAY DIFFRACTION 2.300Å

e1s2eB1[B:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; X-RAY DIFFRACTION 2.300Å

e1tjaC1[C:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1tjaD1[D:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1tjaE1[E:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuA1[A:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuB1[B:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuC1[C:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuD1[D:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuE1[E:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuF1[F:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuG1[G:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuH1[H:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuI1[I:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuJ1[J:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuK1[K:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuL1[L:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuM1[M:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuN1[N:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuO1[O:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuP1[P:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuQ1[Q:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1zkuR1[R:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpA1[A:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpB1[B:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpC1[C:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpD1[D:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpE1[E:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpF1[F:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpG1[G:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpH1[H:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpI1[I:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpJ1[J:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpK1[K:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpL1[L:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpM1[M:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpN1[N:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpO1[O:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpP1[P:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpQ1[Q:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e1pdpR1[R:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp9 ; ELECTRON MICROSCOPY

e2fl8A2[A:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8B2[B:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8C2[C:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8D2[D:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8E2[E:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8F2[F:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8G2[G:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8H2[H:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8I2[I:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8J2[J:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8K2[K:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8L2[L:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8M2[M:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8N2[N:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8O2[O:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8P2[P:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8Q2[Q:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl8R2[R:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9A2[A:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9B2[B:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9C2[C:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9D2[D:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9E2[E:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9F2[F:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9G2[G:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9H2[H:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9I2[I:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9J2[J:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9K2[K:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9L2[L:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9M2[M:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9N2[N:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9O2[O:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9P2[P:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9Q2[Q:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e2fl9R2[R:1-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate structural protein Gp10 ; ELECTRON MICROSCOPY

e5hx2G1[G:1-143] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp10 ; ELECTRON MICROSCOPY

e5hx2H2[H:1-143] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp10 ; ELECTRON MICROSCOPY

e5hx2I1[I:1-143] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp10 ; ELECTRON MICROSCOPY

e5iv5c2[c:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5d2[d:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5e2[e:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5z1[z:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5AA1[AA:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5AB2[AB:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5CC2[CC:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5CD2[CD:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5CE1[CE:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5EF2[EF:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5EG1[EG:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5EH2[EH:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5GI1[GI:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5GJ2[GJ:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5HA2[HA:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7H1[H:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7V2[V:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7W2[W:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7X1[X:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7l2[l:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7m2[m:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7n1[n:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7AB2[AB:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7AC1[AC:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7AD2[AD:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7CD2[CD:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7CE2[CE:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7CF1[CF:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7EF1[EF:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7EG2[EG:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7FA2[FA:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5F2[F:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5G1[G:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5H2[H:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7F1[F:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv7G1[G:1-168] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp9 ; ELECTRON MICROSCOPY

e5iv5I1[I:1-151] nonrep Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Baseplate wedge protein gp10 ; ELECTRON MICROSCOPY

F: Unmapped domains

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

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