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X - Possible homology level

H - Homology level

T - Topology level

F - Family level

* - Provisional representative


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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

X: Ribosomal protein L22e
H: Ribosomal protein L22e
T: Ribosomal protein L22e
F: Ribosomal_L22e

PF01776

Representatives:

e4v8pAM1[AM:12-111] nonrep Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

RIBOSOMAL PROTEIN L22 ; X-RAY DIFFRACTION 3.52Å

e3zf7V1[V:21-124] nonrep Image Pymol Jmol Links: PDB, SCOP, CATH Obsolete PDB

e6z6lLU1[LU:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e6zmeLU1[LU:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e6zmiLU1[LU:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e6ylxU1[U:9-114] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e6lqmd1[d:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e6lsrd1[d:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e6lssd1[d:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e6lu8d1[d:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e6w6lV1[V:18-116] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e6z6mLU1[LU:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e6z6nLU1[LU:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e6zm7LU1[LU:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e6zmoLU1[LU:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e6m62U1[U:9-114] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e6ylgU1[U:12-112] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e6ylhU1[U:12-112] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e6ylyU1[U:9-112] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e6swaS1[S:16-116] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e6xa1LU1[LU:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Heparin-binding protein HBp15 ; ELECTRON MICROSCOPY

e6zj3Lj1[Lj:60-160] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein eL22 ; ELECTRON MICROSCOPY

e6zu5LU01[LU0:10-106] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

eL22 ; ELECTRON MICROSCOPY

e7btbU1[U:11-114] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e7a01821[82:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein L22 ; ELECTRON MICROSCOPY

e7bhpLU1[LU:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e6zvk821[82:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein L22 ; ELECTRON MICROSCOPY

e7nfxU1[U:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein L22 ; ELECTRON MICROSCOPY

e7nwiU1[U:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7o7yBU1[BU:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein eL22 ; ELECTRON MICROSCOPY

e7o7zBU1[BU:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein eL22 ; ELECTRON MICROSCOPY

e7o80BU1[BU:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein eL22 ; ELECTRON MICROSCOPY

e7o81BU1[BU:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein eL22 ; ELECTRON MICROSCOPY

e7nwgU31[U3:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

L22 ; ELECTRON MICROSCOPY

e7nwhU1[U:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

L22 ; ELECTRON MICROSCOPY

e7cpuLU1[LU:17-116] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7olcLU1[LU:16-116] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-like protein ; ELECTRON MICROSCOPY

e7cpvLU1[LU:17-116] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7oldLU1[LU:17-116] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-like protein ; ELECTRON MICROSCOPY

e7qepN21[N2:8-103] Image Pymol Jmol Links: PDB, SCOP, CATHDOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7qwrU1[U:17-121] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7qwqU1[U:17-118] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein L22 ; ELECTRON MICROSCOPY

e7qwsU1[U:17-121] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein L22 ; ELECTRON MICROSCOPY

e7toqAL221[AL22:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

eL22 ; ELECTRON MICROSCOPY

e7f5sLU1[LU:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7oycU11[U1:19-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7zjxLX1[LX:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein eL22 ; ELECTRON MICROSCOPY

e7qiwW1[W:15-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein eL22 ; ELECTRON MICROSCOPY

e7qizW1[W:15-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein eL22 ; ELECTRON MICROSCOPY

e7pwgU1[U:18-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein eL22 ; ELECTRON MICROSCOPY

e7pwoU21[U2:16-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein eL22 ; ELECTRON MICROSCOPY

e7pzy51[5:10-112] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal 60S subunit protein L22B ; ELECTRON MICROSCOPY

e7q0851[5:10-112] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal 60S subunit protein L22B ; ELECTRON MICROSCOPY

e7q0f51[5:10-112] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal 60S subunit protein L22B ; ELECTRON MICROSCOPY

e7q0p51[5:10-112] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal 60S subunit protein L22B ; ELECTRON MICROSCOPY

e7q0r51[5:10-112] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal 60S subunit protein L22B ; ELECTRON MICROSCOPY

e7z34U1[U:9-112] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e7torAL221[AL22:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

eL22 ; ELECTRON MICROSCOPY

e7ucjU1[U:18-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7uckU1[U:18-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7oyaU11[U1:33-129] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein L22 ; ELECTRON MICROSCOPY

e7oybU11[U1:33-129] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein L22 ; ELECTRON MICROSCOPY

e7oydU1[U:18-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-like ; ELECTRON MICROSCOPY

e7qvpLU1[LU:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7qvpMU1[MU:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e8a3dO1[O:18-116] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7qggV1[V:18-116] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7zjwLX1[LX:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein eL22 ; ELECTRON MICROSCOPY

e7qcaLU01[LU0:8-107] Image Pymol Jmol Links: PDB, SCOP, CATH

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7qjhLU01[LU0:8-107] Image Pymol Jmol Links: PDB, SCOP, CATH

e7qjhKU01[KU0:8-107] Image Pymol Jmol Links: PDB, SCOP, CATH

e8esqU1[U:9-106] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e8esrU1[U:9-106] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e8etcU1[U:9-106] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e8etgU1[U:9-106] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e8eugU1[U:9-106] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e8euiU1[U:9-106] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7nacU1[U:11-112] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e7nadU1[U:11-112] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e7r72U1[U:11-112] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e7r7aU1[U:11-112] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e7u0hU1[U:9-114] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e7ug6U1[U:9-114] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e8b5lU1[U:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e8b6cU1[U:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 (Fragment) ; ELECTRON MICROSCOPY

e7tm3U1[U:17-118] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

eL22 ; ELECTRON MICROSCOPY

e7tutU1[U:17-118] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

eL22 ; ELECTRON MICROSCOPY

e8br3LU01[LU0:8-107] Image Pymol Jmol Links: PDB, SCOP, CATH

e8btkBU1[BU:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e8g5yLU1[LU:18-116] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e8g5zLU1[LU:18-116] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e8g60LU1[LU:18-116] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

eL22 ; ELECTRON MICROSCOPY

e8g61LU1[LU:18-116] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e8g6jLU1[LU:18-116] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e8glpLU1[LU:18-116] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7xnxLU1[LU:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e7xnyLU1[LU:17-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e8hfrUF1[UF:7-121] Image Pymol Jmol Links: PDB, SCOP, CATH

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e7uooU1[U:9-114] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e7uqbU1[U:9-114] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e7uqzU1[U:9-114] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e7v08U1[U:9-114] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-A ; ELECTRON MICROSCOPY

e8i9xLU1[LU:16-120] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-like protein ; ELECTRON MICROSCOPY

e8i9yLU1[LU:16-120] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-like protein ; ELECTRON MICROSCOPY

e8i9zLU1[LU:16-120] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-like protein ; ELECTRON MICROSCOPY

e8ia0LU1[LU:16-120] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-like protein ; ELECTRON MICROSCOPY

e7z3nLU1[LU:16-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-like protein ; ELECTRON MICROSCOPY

e7z3oLU1[LU:16-119] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-like protein ; ELECTRON MICROSCOPY

e8br8LV1[LV:12-111] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal L22e ; ELECTRON MICROSCOPY

e8brmLV1[LV:9-111] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein L22e ; ELECTRON MICROSCOPY

e8bsiLV1[LV:11-118] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal L22e ; ELECTRON MICROSCOPY

e8bsjLV1[LV:9-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal L22e ; ELECTRON MICROSCOPY

e8btdLV1[LV:9-123] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein L22e ; ELECTRON MICROSCOPY

e8btrLV1[LV:9-111] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

Ribosomal protein L22e ; ELECTRON MICROSCOPY

e8p5dLU01[LU0:8-107] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

; ELECTRON MICROSCOPY

e8fkzLF1[LF:17-119] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

; ELECTRON MICROSCOPY

e8p2kBU1[BU:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e8idtd1[d:17-120] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

; ELECTRON MICROSCOPY

e8azwK1[K:19-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

; ELECTRON MICROSCOPY

e8b2lK31[K3:19-117] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein L22-2-like ; ELECTRON MICROSCOPY

e8bpoT21[T2:17-118] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

; ELECTRON MICROSCOPY

e8bhfH11[H1:17-115] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

; ELECTRON MICROSCOPY

e8a98U1[U:2-122] Image Pymol Jmol Links: PDB, SCOP, CATH

Putative 60S ribosomal protein L22 ; ELECTRON MICROSCOPY

e8q5i51[5:12-112] Image Pymol Jmol Links: PDB, SCOP, CATHDOI

; ELECTRON MICROSCOPY

Previous

e4v6iBW1[BW:6-110] nonrep Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI

60S ribosomal protein rpL22 (L22e) ; ELECTRON MICROSCOPY

X: LuxS, MPP, ThrRS/AlaRS common domain

looks like an elaborated ferredoxin

X: ClpS-like

contains a HTH motif

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