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
Representatives:
e1nvuS1[S:566-1046] nonrep Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless protein homolog 1 ; ligands: PO4 ; X-RAY DIFFRACTION 2.20Å
e8be2S1[S:567-1043] Image Pymol Jmol Links: PDB, SCOP, CATH
; ligands: SO4 ; X-RAY DIFFRACTION 1.897935059Å
e8be4S1[S:570-652,S:673-1044] Image Pymol Jmol Links: PDB, SCOP, CATH
; X-RAY DIFFRACTION 1.895400854Å
e8be5AAZA1[AAZA:570-1043] Image Pymol Jmol Links: PDB, SCOP, CATH
; X-RAY DIFFRACTION 3.13Å
e6axfA1[A:8-387] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
RAS guanyl-releasing protein 2 ; X-RAY DIFFRACTION 3.10Å
e6axfC1[C:7-387] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
RAS guanyl-releasing protein 2 ; X-RAY DIFFRACTION 3.10Å
e6axfE1[E:7-387] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
RAS guanyl-releasing protein 2 ; X-RAY DIFFRACTION 3.10Å
e6axfG1[G:7-387] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
RAS guanyl-releasing protein 2 ; X-RAY DIFFRACTION 3.10Å
e6axfI1[I:7-387] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
RAS guanyl-releasing protein 2 ; X-RAY DIFFRACTION 3.10Å
e6axfK1[K:8-387] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
RAS guanyl-releasing protein 2 ; X-RAY DIFFRACTION 3.10Å
e6axfM1[M:6-387] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
RAS guanyl-releasing protein 2 ; X-RAY DIFFRACTION 3.10Å
e6axfO1[O:7-387] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
RAS guanyl-releasing protein 2 ; X-RAY DIFFRACTION 3.10Å
e1xd2C1[C:566-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless protein homolog 1 ; ligands: PO4 ; X-RAY DIFFRACTION 2.7Å
e2ii0A1[A:566-1045] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SON OF SEVENLESS HOMOLOG 1 ; X-RAY DIFFRACTION 2.02Å
e1nvwS1[S:566-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SON OF SEVENLESS PROTEIN HOMOLOG 1 ; ligands: PO4 ; X-RAY DIFFRACTION 2.7Å
e1nvvS1[S:566-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless protein homolog 1 ; ligands: PO4 ; X-RAY DIFFRACTION 2.18Å
e4nyiS1[S:566-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: 2PX ; X-RAY DIFFRACTION 2.961Å
e4nyjS1[S:566-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SON OF SEVENLESS HOMOLOG 1 ; ligands: 2PZ ; X-RAY DIFFRACTION 2.85Å
e4nymS1[S:566-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SON OF SEVENLESS HOMOLOG 1 ; ligands: RND ; X-RAY DIFFRACTION 3.55Å
e1bkdS1[S:568-653,S:676-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SON OF SEVENLESS-1 ; X-RAY DIFFRACTION 2.8Å
e1nvxS1[S:566-653,S:673-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless protein homolog 1 ; ligands: PO4 ; X-RAY DIFFRACTION 3.20Å
e1xd4A1[A:555-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless protein homolog 1 ; X-RAY DIFFRACTION 3.62Å
e1xd4B1[B:555-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless protein homolog 1 ; X-RAY DIFFRACTION 3.62Å
e4us1S1[S:565-1045] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SON OF SEVENLESS HOMOLOG 1 ; ligands: L71 ; X-RAY DIFFRACTION 2.65Å
e4uruS1[S:567-1045] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SON OF SEVENLESS HOMOLOG 1 ; ligands: 6W2 ; X-RAY DIFFRACTION 2.83Å
e4urvS1[S:568-1045] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SON OF SEVENLESS HOMOLOG 1 ; ligands: FMT,UMK ; X-RAY DIFFRACTION 2.58Å
e4urwS1[S:566-1045] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SON OF SEVENLESS HOMOLOG 1 ; ligands: DXO ; X-RAY DIFFRACTION 2.76Å
e4urxS1[S:566-1045] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SON OF SEVENLESS HOMOLOG 1 ; ligands: FK1,FMT,HXY ; X-RAY DIFFRACTION 2.48Å
e4uryS1[S:566-651,S:673-1045] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SON OF SEVENLESS HOMOLOG 1 ; ligands: RV1 ; X-RAY DIFFRACTION 2.47Å
e4urzS1[S:567-1045] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SON OF SEVENLESS HOMOLOG 1 ; ligands: VJP ; X-RAY DIFFRACTION 2.36Å
e4us0S1[S:567-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; X-RAY DIFFRACTION 2.17Å
e4us2S1[S:566-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SON OF SEVENLESS HOMOLOG 1 ; ligands: L7S ; X-RAY DIFFRACTION 2.48Å
e1xdvA1[A:566-653,A:676-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SON OF SEVENLESS PROTEIN HOMOLOG 1 ; X-RAY DIFFRACTION 4.1Å
e1xdvB1[B:566-653,B:676-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
SON OF SEVENLESS PROTEIN HOMOLOG 1 ; X-RAY DIFFRACTION 4.1Å
e3ksyA1[A:555-1045] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; X-RAY DIFFRACTION 3.18Å
e5wfoN1[N:566-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: 5UU ; X-RAY DIFFRACTION 1.99Å
e5wfpN1[N:566-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: 5UX ; X-RAY DIFFRACTION 2.08Å
e5wfqN1[N:566-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: 5UV ; X-RAY DIFFRACTION 2.26Å
e5wfrN1[N:566-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: 5UW ; X-RAY DIFFRACTION 2.46Å
e6d55B1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FMT,FWA,GOL ; X-RAY DIFFRACTION 1.68Å
e6d5vS1[S:566-1045] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FVY ; X-RAY DIFFRACTION 2.04Å
e6d56B1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FMT,FVM,GOL ; X-RAY DIFFRACTION 1.68Å
e6d59B1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FMT,FVJ,GOL ; X-RAY DIFFRACTION 1.7Å
e6d5eB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: CL,FMT,FVG,GOL ; X-RAY DIFFRACTION 1.75Å
e6d5gB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: BME,CL,FMT,FVD,GOL ; X-RAY DIFFRACTION 1.92Å
e6d5hB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: CL,FMT,FV7,GOL ; X-RAY DIFFRACTION 1.8Å
e6d5jB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FMT,FV4,GOL ; X-RAY DIFFRACTION 1.75Å
e6d5lB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FMT,FW7,GOL ; X-RAY DIFFRACTION 1.7Å
e6d5mS1[S:566-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FW4 ; X-RAY DIFFRACTION 2.08Å
e6bviB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: EC4,FMT,GOL ; X-RAY DIFFRACTION 1.746Å
e6bvjB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: EAS,FMT,GOL ; X-RAY DIFFRACTION 1.747Å
e6bvkB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: EAV,FMT,GOL ; X-RAY DIFFRACTION 1.799Å
e6bvlB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: EBY,FMT,GOL ; X-RAY DIFFRACTION 1.748Å
e6bvmB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: EBV,FMT,GOL ; X-RAY DIFFRACTION 1.796Å
e5ovfA1[A:560-1045] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: AWT,EDO ; X-RAY DIFFRACTION 2.01Å
e6eieA1[A:561-1040] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 2 ; X-RAY DIFFRACTION 2.72Å
e5ovhA1[A:560-652,A:672-1045] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: AWW,EDO ; X-RAY DIFFRACTION 2.3Å
e6eplS1[S:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; X-RAY DIFFRACTION 2.55Å
e6epmS1[S:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: BQ5,GOL ; X-RAY DIFFRACTION 2.5Å
e6epnS1[S:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: BQ2,DMS,GOL ; X-RAY DIFFRACTION 2.50Å
e6epoS1[S:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: BPW ; X-RAY DIFFRACTION 2.40Å
e6eppS1[S:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: BOQ ; X-RAY DIFFRACTION 2.4Å
e5ovdA1[A:560-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: EDO ; X-RAY DIFFRACTION 1.90Å
e5oveA1[A:560-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: AXE,EDO ; X-RAY DIFFRACTION 1.85Å
e5ovgA1[A:563-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: AWZ,EDO ; X-RAY DIFFRACTION 2.30Å
e5oviA1[A:566-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: AXH,EDO ; X-RAY DIFFRACTION 2.20Å
e6cuoB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FFS,FMT,GOL ; X-RAY DIFFRACTION 1.73Å
e6cupB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FFV,FMT,GOL ; X-RAY DIFFRACTION 1.83Å
e6curB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FFY,FMT,GOL ; X-RAY DIFFRACTION 1.73Å
e6d5wS1[S:566-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FVV ; X-RAY DIFFRACTION 2.47Å
e6v94B1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FMT,GOL,QTV ; X-RAY DIFFRACTION 1.800Å
e6v9fB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FMT,GOL,QTS ; X-RAY DIFFRACTION 1.849Å
e6v9jB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FMT,GOL,QTM ; X-RAY DIFFRACTION 1.760Å
e6v9lB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FMT,GOL,QTJ ; X-RAY DIFFRACTION 1.698Å
e6v9mB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FMT,GOL,QTG ; X-RAY DIFFRACTION 1.648Å
e6v9nB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FMT,GOL,QTD ; X-RAY DIFFRACTION 1.648Å
e6scmA1[A:564-1043] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: EDO,IMD,L7H ; X-RAY DIFFRACTION 1.866Å
e6sfrA1[A:563-1042] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: IMD,LBK ; X-RAY DIFFRACTION 1.917Å
e6sfrB1[B:565-1042] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: IMD,LBK ; X-RAY DIFFRACTION 1.917Å
e6v9oB1[B:565-1046] Image Pymol Jmol Links: PDB, SCOP, CATH
Son of sevenless homolog 1 ; ligands: FMT,GOL,QTA ; X-RAY DIFFRACTION 1.799Å
e7kfzB1[B:566-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ELECTRON MICROSCOPY
e7aviA1[A:563-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: S2Q ; X-RAY DIFFRACTION 1.93Å
e7avlB1[B:565-1042] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: IMD,S2Z ; X-RAY DIFFRACTION 1.718Å
e7avsA1[A:563-1042] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: IMD,S3Q ; X-RAY DIFFRACTION 2.28Å
e7avsB1[B:565-1042] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: IMD,S3Q ; X-RAY DIFFRACTION 2.28Å
e7avtA1[A:563-1042] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: IMD,S3T ; X-RAY DIFFRACTION 1.88Å
e7avtB1[B:565-1042] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: IMD,S3T ; X-RAY DIFFRACTION 1.88Å
e7avuA1[A:563-1042] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: IMD,S3Z ; X-RAY DIFFRACTION 2.075Å
e7avuB1[B:565-1042] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: S3Z ; X-RAY DIFFRACTION 2.075Å
e7avvA1[A:565-1042] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: IMD,S2W ; X-RAY DIFFRACTION 2.12Å
e7aviB1[B:563-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: S2Q ; X-RAY DIFFRACTION 1.93Å
e7avlA1[A:563-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: IMD,S2Z ; X-RAY DIFFRACTION 1.718Å
e7nzzA1[A:904-1306] Image Pymol Jmol Links: PDB, SCOP, CATH
Cell division control protein 25 ; X-RAY DIFFRACTION 2.45Å
e7nzzB1[B:904-1305] Image Pymol Jmol Links: PDB, SCOP, CATH
Cell division control protein 25 ; X-RAY DIFFRACTION 2.45Å
e7ukrA1[A:568-651,A:671-1042] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: NKF ; X-RAY DIFFRACTION 2.5Å
e7ukrB1[B:576-651,B:671-1042] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: NKF ; X-RAY DIFFRACTION 2.5Å
e7uksA1[A:567-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: NL0 ; X-RAY DIFFRACTION 2.29Å
e8be6S1[S:569-653,S:675-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; X-RAY DIFFRACTION 2.89880249261Å
e8be7S1[S:567-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; X-RAY DIFFRACTION 3Å
e8be8S1[S:567-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FMT ; X-RAY DIFFRACTION 2.3962602619Å
e8be9S1[S:567-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; ligands: FMT ; X-RAY DIFFRACTION 2.509612595Å
e8beaS1[S:567-1044] Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Son of sevenless homolog 1 ; X-RAY DIFFRACTION 2.47Å
e4jgwA1[A:50-402,A:427-512] nonrep Image Pymol Jmol Links: PDB, SCOP, CATH, PubMed, DOI
Ral guanine nucleotide dissociation stimulator-like 2 ; X-RAY DIFFRACTION 2.3Å
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
few secondary structure elementsstabilized by cofactors or disulfides
extended segmentsextended, non-globular segments, frequently bind to other proteins to form complexes