- TIM beta/alpha-barrel (51350)
contains parallel beta-sheet barrel, closed; n=8, S=8; strand order 12345678
the first seven superfamilies have similar phosphate-binding sites
- YerB-like (995811)
3 layers: b/b/a; central mixed beta-sheet of 9 strands, order 541329678; strands 3 and 7 are antiparallel to the rest; an unusual "over the other end" connection between strands 3 and 4
- CdCA1 repeat-like (995805)
contains two parallel beta-strands of four strands each; the sheets contact each other with edges at a right angle
- EreA/ChaN-like (995798)
Core: 3 layers: a/b/a; parallel beta-sheet of 5 strands, order:51423;
- CobE/GbiG C-terminal domain-like (995779)
3 layers: a/b/a; mixed beta-sheet of 5 strands, order 32154; strand 5 is antiparallel to the rest
- AtpF-like (995773)
3 layers, a/b/a; core: parallel beta-sheet of 4 strands, order 2134
- NAD(P)-binding Rossmann-fold domains (51734)
core: 3 layers, a/b/a; parallel beta-sheet of 6 strands, order 321456
The nucleotide-binding modes of this and the next two folds/superfamilies are similar
- FAD/NAD(P)-binding domain (51904)
core: 3 layers, b/b/a; central parallel beta-sheet of 5 strands, order 32145; top antiparallel beta-sheet of 3 strands, meander
- Nucleotide-binding domain (51970)
3 layers: a/b/a; parallel beta-sheet of 5 strands, order 32145; Rossmann-like
- MurCD N-terminal domain (51983)
3 layers: a/b/a; parallel beta-sheet of 5 strands, order 32145; incomplete Rossmann-like fold; binds UDP group
- 7-stranded beta/alpha barrel (51988)
variant of beta/alpha barrel; parallel beta-sheet barrel, closed, n=7, S=8; strand order 1234567; some members may have fewer strands
- PFL-like glycyl radical enzymes (51997)
contains: barrel, closed; n=10, S=10; accommodates a hairpin loop inside the barrel
- The "swivelling" beta/beta/alpha domain (52008)
3 layers: b/b/a; the central sheet is parallel, and the other one is antiparallel; there are some variations in topology
this domain is thought to be mobile in most multi-domain proteins known to contain it
- Barstar-like (52037)
2 layers, a/b; parallel beta-sheet of 3 strands, order 123
- MurF and HprK N-domain-like (63417)
core: 3 layers, a/b/a; parallel beta-sheet of 4 strands, order 1234; structural similarity of the MurF and HprK extends beyond the core.
- Leucine-rich repeat, LRR (right-handed beta-alpha superhelix) (52046)
2 curved layers, a/b; parallel beta-sheet; order 1234...N; there are sequence similarities between different superfamilies
- Ribosomal proteins L15p and L18e (52079)
core: three turns of irregular (beta-beta-alpha)n superhelix
- SpoIIaa-like (52086)
core: 4 turns of a (beta-alpha)n superhelix
- ClpP/crotonase (52095)
core: 4 turns of (beta-beta-alpha)n superhelix
- BRCT domain (52112)
3 layers, a/b/a; core: parallel beta-sheet of 4 strands, order 2134
- Lumazine synthase (52120)
3 layers, a/b/a; core: parallel beta-sheet of 4 strands, order 2134
- Uracil-DNA glycosylase-like (52140)
3 layers, a/b/a; core: parallel beta-sheet of 4 strands, order 2134
- Creatininase (102214)
3 layers, a/b/a; core: parallel beta-sheet of 4 strands, order 2134
- DNA polymerase III psi subunit (102219)
3 layers, a/b/a; parallel beta-sheet of 4 strands, order 2134
- Initiation factor IF2/eIF5b, domain 3 (52155)
3 layers, a/b/a; core: parallel beta-sheet of 4 strands, order 2134
- Aminoacid dehydrogenase-like, N-terminal domain (53222)
core: 3 layers: a/b/a; parallel beta-sheet of 4 strands; 2134
- Toprim domain (110454)
3 layers, a/b/a; parallel beta-sheet of 4 strands, order 2134
- Ribosomal protein L13 (52160)
3 layers, a/b/a; core: parallel beta-sheet of 4 strands, order 3214
- Ribosomal protein L4 (52165)
3 layers, a/b/a; core: parallel beta-sheet of 4 strands, order 1423
- Nqo1 FMN-binding domain-like (142018)
3 layers, a/b/a; parallel beta-sheet of 4 strands, order 3214
- Flavodoxin-like (52171)
3 layers, a/b/a; parallel beta-sheet of 5 strand, order 21345
- Methylglyoxal synthase-like (52334)
3 layers, a/b/a; parallel beta-sheet of 5 strands, order 32145
- Ferredoxin reductase-like, C-terminal NADP-linked domain (52342)
3 layers, a/b/a; parallel beta-sheet of 5 strands, order 32145
- Adenine nucleotide alpha hydrolase-like (52373)
core: 3 layers, a/b/a ; parallel beta-sheet of 5 strands, order 32145
- Nucleoside phosphorylase/phosphoribosyltransferase catalytic domain (52417)
3 layers: a/b/a; parallel beta-sheet of 5 strands, order 32145; Rossmann-like
- Cryptochrome/photolyase, N-terminal domain (52424)
3 layers: a/b/a; parallel beta-sheet of 5 strands, order 32145; Rossmann-like
- DsrEFH-like (75168)
3 layers: a/b/a, core: parallel beta-sheet of 5 strands, order 43215
- PIN domain-like (88722)
3 layers, a/b/a; core: parallel beta-sheet of 5 strands, order 32145
- Ribose/Galactose isomerase RpiB/AlsB (89622)
3 layers: a/b/a, core: parallel beta-sheet of 5 strands, order 21354; topological similarity to a part of the arginase/deacetylase fold
- alpha/beta knot (75216)
core: 3 layers: a/b/a, parallel beta-sheet of 5 strands, order 21435; contains a deep trefoil knot
- PreATP-grasp domain (52439)
3 layers: a/b/a; parallel or mixed beta-sheet of 4 to 6 strands
possible rudiment form of Rossmann-fold domain
- DHS-like NAD/FAD-binding domain (52466)
3 layers: a/b/a; parallel beta-sheet of 6 strands, order 321456; Rossmann-like
- Tubulin nucleotide-binding domain-like (52489)
3 layers: a/b/a; parallel beta-sheet of 6 strands, order 321456
- Isochorismatase-like hydrolases (52498)
3 layers: a/b/a; parallel beta-sheet of 6 strands, order 321456
- Dipeptide transport protein (63991)
3 layers: a/b/a; parallel beta-sheet of 6 strands, order 321456; also contains a C-terminal alpha+beta subdomain
- Homo-oligomeric flavin-containing Cys decarboxylases, HFCD (52506)
3 layers: a/b/a; parallel beta-sheet of 6 strands, order 321456
- HAD-like (56783)
3 layers: a/b/a; parallel beta-sheet of 6 strands, order 321456
- NagB/RpiA/CoA transferase-like (100949)
core: 3 layers: a/b/a; parallel or mixed beta-sheet of 6 strands, order 321456
- Hypothetical protein MTH777 (MT0777) (75180)
3 layers: a/b/a; parallel beta-sheet of 6 strands, order 321456
- Thiamin pyrophosphokinase, catalytic domain (63998)
3 layers: a/b/a; parallel beta-sheet of 6 strands, order 432156
- Undecaprenyl diphosphate synthase (64004)
3 layers: a/b/a; parallel beta-sheet of 6 strands, order 342156
- F420-dependent methylenetetrahydromethanopterin dehydrogenase (MTD) (102323)
3 layers: a/b/a; parallel beta-sheet of 6 strands, order 213456
- Thiamin diphosphate-binding fold (THDP-binding) (52517)
3 layers: a/b/a; parallel beta-sheet of 6 strands, order 213465
- P-loop containing nucleoside triphosphate hydrolases (52539)
3 layers: a/b/a, parallel or mixed beta-sheets of variable sizes
- PTS IIb component (52727)
3 layers: a/b/a, parallel beta-sheet of 6 strands, order 324156
- DNA polymerase III chi subunit (102399)
3 layers, a/b/a; parallel beta-sheet of 7 strands, order 7165243
- Nicotinate mononucleotide:5,6-dimethylbenzimidazole phosphoribosyltransferase (CobT) (52732)
3 layers: a/b/a, parallel beta-sheet of 7 strands, order 3214567
- CofD-like (142337)
3 layers: a/b/a, parallel beta-sheet of 7 strands, order 3214567; topological similarity to the CobT-like fold (scop_cf 52732)
- MCP/YpsA-like (102404)
3 layers: a/b/a, parallel beta-sheet of 7 strands, order 4321567
- Methylesterase CheB, C-terminal domain (52737)
3 layers: a/b/a, parallel beta-sheet of 7 strands, order 3421567
- Subtilisin-like (52742)
3 layers: a/b/a, parallel beta-sheet of 7 strands, order 2314567; left-handed crossover connection between strands 2 & 3
- Indigoidine synthase A-like (110580)
core: 3 layers, a/b/a; parallel beta-sheet of 7 strands, order 2134756
- Arginase/deacetylase (52767)
3 layers: a/b/a, parallel beta-sheet of 8 strands, order 21387456
- Alpha-2,3/8-sialyltransferase CstII (102413)
3 layers: a/b/a; parallel beta-sheet of 8 strands, order 54321678
- Cell-division inhibitor MinC, N-terminal domain (64042)
beta(2)-(alpha-beta)2-beta; 2 layers, a/b; mixed beta-sheet of 5 strands, order 12345; strands 1 & 5 are antiparallel to the rest
- DTD-like (69499)
beta(2)-(alpha-beta)2-beta(3); 3 layers, a/b/b; some topological similarity to the N-terminal domain of MinC
- CoA-dependent acyltransferases (52776)
core: 2 layers, a/b; mixed beta-sheet of 6 strands, order 324561; strands 3 & 6 are antiparallel to the rest
- Phosphotyrosine protein phosphatases I-like (52787)
3 layers: a/b/a; parallel beta-sheet of 4 strands, order 2134
- (Phosphotyrosine protein) phosphatases II (52798)
core: 3 layers, a/b/a; parallel beta-sheet of 4 strands, order 1423
- Rhodanese/Cell cycle control phosphatase (52820)
3 layers: a/b/a; parallel beta-sheet of 5 strands, order 32451
- Thioredoxin fold (52832)
core: 3 layers, a/b/a; mixed beta-sheet of 4 strands, order 4312; strand 3 is antiparallel to the rest
- Peptidyl-tRNA hydrolase II (102461)
3 layers: a/b/a; mixed beta-sheet of 4 strands, order 2143, strand 4 is antiparallel to the rest
- TK C-terminal domain-like (52921)
3 layers: a/b/a; mixed beta-sheet of 5 strands, order 13245, strand 1 is antiparallel to the rest
- Pyruvate kinase C-terminal domain-like (52934)
3 layers: a/b/a; mixed beta-sheet of 5 strands, order 32145, strand 5 is antiparallel to the rest
- Anticodon-binding domain-like (52953)
3 layers: a/b/a; mixed beta-sheet of five strands, order 21345; strand 4 is antiparallel to the rest
- MTH938-like (64075)
core: 3 layers, b+a/b/a ; the central mixed sheet of 5 strands: order 21534; strand 2 is antiparallel to the rest
- Restriction endonuclease-like (52979)
core: 3 layers, a/b/a; mixed beta-sheet of 5 strands, order 12345; strands 2 &, in some families, 5 are antiparallel to the rest
- Resolvase-like (53040)
Core: 3 layers: a/b/a; mixed beta-sheet of 5 strands, order 21345; strand 5 is antiparallel to the rest
- PTS system fructose IIA component-like (53061)
3 layers: a/b/a; mixed beta-sheet of 5 strands, order 21345; strand 5 is antiparallel to the rest
- Ribonuclease H-like motif (53066)
3 layers: a/b/a; mixed beta-sheet of 5 strands, order 32145; strand 2 is antiparallel to the rest
- Phosphorylase/hydrolase-like (53162)
core: 3 layers, a/b/a ; mixed sheet of 5 strands: order 21354; strand 4 is antiparallel to the rest; contains crossover loops
- Molybdenum cofactor biosynthesis proteins (53217)
3 layers: a/b/a; mixed beta-sheet of 5 strands; order: 21354, strand 5 is antiparallel to the rest; permutation of the Phosphorylase/hydrolase-like fold
- Bacterial fluorinating enzyme, N-terminal domain (102521)
3 layers: a/b/a; mixed beta-sheet of 6 strands; order: 213546, strand 5 is antiparallel to the rest; topological similarity to the MogA-like family fold
- Caspase-like (52128)
3 layers, a/b/a; core: mixed beta-sheet of 6 strands, order 213456, strand 6 is antiparallel to the rest
- Macro domain-like (52948)
3 layers: a/b/a; mixed beta-sheet of 6 strands, order 165243, strand 3 is antiparallel to the rest
- MurD-like peptide ligases, peptide-binding domain (53243)
3 layers: a/b/a; mixed beta-sheet of 6 strands, order 126345; strand 1 is antiparallel to the rest
- Phosphoglycerate mutase-like (53253)
core: 3 layers, a/b/a; mixed beta-sheet of 6 strands, order 324156; strand 5 is antiparallel to the rest
- PRTase-like (53270)
core: 3 layers, a/b/a; mixed beta-sheet of 6 strands, order 321456; strand 3 is antiparallel to the rest
- vWA-like (53299)
core: 3 layers, a/b/a; mixed beta-sheet of 6 strands, order 321456; strand 3 is antiparallel to the rest
- Pyruvate-ferredoxin oxidoreductase, PFOR, domain III (53322)
3 layers: a/b/a; mixed beta-sheet of 6 strands, order 231456; strand 3 is antiparallel to the rest
- RbsD-like (102545)
3 layers: a/b/a; mixed beta-sheet of 6 strands, order 251634; strand 6 is antiparallel to the rest
- FabD/lysophospholipase-like (52150)
core: 3 layers, a/b/a; mixed beta-sheet of 6 strands, order 432156; strand 4 is antiparallel to the rest
- L-sulfolactate dehydrogenase-like (89732)
core: 3 layers, a/b/a; mixed sheet of 7 strands, order 1237456; strands 1, 6 and 7 are antiparallel to the rest
- Formyltransferase (53327)
3 layers: a/b/a; mixed beta-sheet of 7 strands, order 3214567; strand 6 is antiparallel to the rest
- S-adenosyl-L-methionine-dependent methyltransferases (53334)
core: 3 layers, a/b/a; mixed beta-sheet of 7 strands, order 3214576; strand 7 is antiparallel to the rest
- LmbE-like (102587)
3 layers, a/b/a; mixed beta-sheet of 7 strands, order 3214576; strand 7 is antiparallel to the rest; topological similarity to SAM-dependent methyltransferases
- PLP-dependent transferase-like (53382)
main domain: 3 layers: a/b/a, mixed beta-sheet of 7 strands, order 3245671; strand 7 is antiparallel to the rest
- Nucleotide-diphospho-sugar transferases (53447)
3 layers: a/b/a; mixed beta-sheet of 7 strands, order 3214657; strand 6 is antiparallel to the rest
- RibA-like (142694)
3 layers: a/b/a; mixed beta-sheet of 7 strands, order 1235467, strands 1 and 3 are antiparallel to the rest; partial topological similarity to some alpha/beta hydrolases (scop_cf 53473)
- Activating enzymes of the ubiquitin-like proteins (69571)
3 layers: a/b/a; mixed beta-sheet of 8 strands, order 32145678; strands 6 and 8 are antiparallel to the rest
- alpha/beta-Hydrolases (53473)
core: 3 layers, a/b/a; mixed beta-sheet of 8 strands, order 12435678, strand 2 is antiparallel to the rest
- Nucleoside hydrolase (53589)
core: 3 layers, a/b/a ; mixed beta-sheet of 8 strands, order 32145687; strand 7 is antiparallel to the rest
- Dihydrofolate reductase-like (53596)
3 layers: a/b/a; mixed beta-sheet of 8 strands, order 34251687; strand 8 is antiparallel to the rest
- Ribokinase-like (53612)
core: 3 layers: a/b/a; mixed beta-sheet of 8 strands, order 21345678, strand 7 is antiparallel to the rest
potential superfamily: members of this fold have similar functions but different ATP-binding sites
- YjeF N-terminal domain-like (64152)
3 layers: a/b/a; mixed (mainly parallel) beta-sheet of 8 strands, order 32145678; strand 8 is antiparallel to the rest
- Carbamate kinase-like (53632)
3 layers: a/b/a; mixed (mainly parallel) beta-sheet of 8 strands, order 34215786; strand 8 is antiparallel to the rest
- 2,3-Bisphosphoglycerate-independent phosphoglycerate mutase, substrate-binding domain (64157)
core:3 layers: a/b/a; mixed beta-sheet of 8 strands, order 45321678, strands 4 and 5 are antiparallel to the rest
- Alkaline phosphatase-like (53648)
core:3 layers: a/b/a; mixed beta-sheet of 8 strands, order 43516728, strand 7 is antiparallel to the rest
- TTHA0583/YokD-like (110709)
3 layers: a/b/a; mixed beta-sheet of 8 strands, order 78612354; strands 3, 4 and 8 are antiparallel to the rest
- Glycerol-3-phosphate (1)-acyltransferase (69592)
3 layers: a/b/a; mixed beta-sheet of 9 strands, order 918736452; strands 1, 2 and 8 are antiparallel to the rest
- AraD/HMP-PK domain-like (53638)
3 layers: a/b/a; mixed (mostly antiparallel) beta-sheet of 9 strands, order 432159876; left-handed crossover between strands 4 and 5
- SurE-like (64166)
3 layers: a/b/a; mixed beta-sheet of 9 strands, order 342156798; strands 3, 8 and 9 are antiparallel to the rest; left-handed crossover connection between strands 6 and 7
- Isocitrate/Isopropylmalate dehydrogenase-like (53658)
consists of two intertwined (sub)domains related by pseudo dyad; duplication
3 layers: a/b/a; single mixed beta-sheet of 10 strands, order 213A945867 (A=10); strands from 5 to 9 are antiparallel to the rest
- Amidase signature (AS) enzymes (75303)
possible duplication: the topologies of N- and C-terminal halves are similar; 3 layers: a/b/a; single mixed beta-sheet of 10 strands, order 213549A867 (A=10); strands from 5 to 9 are antiparallel to the rest
- ATC-like (53670)
consists of two similar domains related by pseudo dyad; duplication
core: 3 layers, a/b/a, parallel beta-sheet of 4 strands, order 2134
- Tryptophan synthase beta subunit-like PLP-dependent enzymes (53685)
consists of two similar domains related by pseudo dyad; duplication
core: 3 layers, a/b/a; parallel beta-sheet of 4 strands, order 3214
- SIS domain (53696)
3 layers: a/b/a; parallel beta-sheet of 5 strands, order 21345
- Formate dehydrogenase/DMSO reductase, domains 1-3 (53705)
contains of two similar intertwined domains related by pseudo dyad; duplication
core: 3 layers: a/b/a; parallel beta-sheet of 5 strands, order 32451
- ALDH-like (53719)
consists of two similar domains with 3 layers (a/b/a) each; duplication
core: parallel beta-sheet of 5 strands, order 32145
- NadA-like (142753)
duplication; consists of three similar domains related by pseudo threefold symmetry; 3 layers, a/b/a; parallel beta sheet, order: 2134
- Aconitase iron-sulfur domain (53731)
consists of three similar domains with 3 layers (a/b/a) each; duplication
core: parallel beta-sheet of 5 strands, order 32145
- Phosphoglucomutase, first 3 domains (53737)
consists of three similar domains with 3 layers (a/b/a) each; duplication
core: mixed beta-sheet of 4 strands, order 2134, strand 4 is antiparallel to the rest
- FucI/AraA N-terminal and middle domains (53742)
consists of two domains of similar topology, 3 layers (a/b/a) each
Domain 1 (1-173) has parallel beta-sheet of 5 strands, order 21345
Domain 2 (174-355) has parallel beta-sheet of 4 strands, order 2134
- YgbK-like (142763)
consists of two domains with partial topological similarity to the P-loop kinases but without the P-loop motif; the domain association results in the formation of a single mixed beta-sheet of 15 strands
- Phosphoglycerate kinase (53747)
consists of two non-similar domains, 3 layers (a/b/a) each
Domain 1 has parallel beta-sheet of 6 strands, order 342156
Domain 2 has parallel beta-sheet of 6 strands, order 321456
- UDP-Glycosyltransferase/glycogen phosphorylase (53755)
consists of two non-similar domains with 3 layers (a/b/a) each
domain 1: parallel beta-sheet of 7 strands, order 3214567
domain 2: parallel beta-sheet of 6 strands, order 321456
- Glutaminase/Asparaginase (53773)
consists of two non-similar alpha/beta domains, 3 layers (a/b/a) each
Domain 1 has mixed beta-sheet of 6 strands, order 213456, strand 6 is antiparallel to the rest; left-handed crossover connection between strands 4 and 5
Domain 2 has parallel beta-sheet of 4 strands, order 1234
- Phosphofructokinase (53783)
consists of two non-similar domains, 3 layers (a/b/a) each
Domain 1 has mixed sheet of 7 strands, order 3214567; strands 3 & 7 are antiparallel to the rest
Domain 2 has parallel sheet of 4 strands, order 2314
- Tetrapyrrole methylase (53789)
consists of two non-similar domains
Domain 1 has parallel sheet of 5 strands, order 32415
Domain 2 has mixed sheet of 5 strands, order 12534; strands 4 & 5 are antiparallel to the rest
- GckA/TtuD-like (82543)
consists of two non-similar domains
Domain 1 has parallel sheet of 6 strands, order 321456, Rossmann-like topology
Domain 2 has mixed sheet of 6 strands, order 126345; strands 5 and 6 are antiparallel to the rest; some similarity to CbiF Domain 2
- DAK1/DegV-like (82548)
2 different domains; d1: [core: 3 layers, a/b/a; parallel sheet of 5 strands, order: 2134]; D2: [2 layers, a/b; mixed sheet of 6 strands, order 321645; strands 2 and 6 are antiparallel to the rest]
- DHH phosphoesterases (64181)
consists of two non-similar domains
Domain 1 has parallel sheet of 6 strands, order 321456
Domain 2 has mixed sheet of 5 strands, order 12345; strands 1 & 4 are antiparallel to the rest
- Glycerate kinase I (110737)
consists of two different alpha/beta domains; (1) of the Flavodoxin-like fold (scop_cf 52171); (2) similar to the Restriction endonuclease-like fold (scop_cf 52979), inserted into domain 1
- PEP carboxykinase-like (53794)
contains a P-loop NTP-binding motif; mixed beta-sheet folds into a barrel-like structure with helices packed on one side
- PEP carboxykinase N-terminal domain (68922)
contains mixed beta-sheets; topology is partly similar to that of the catalytic C-terminal domain
- Chelatase-like (53799)
duplication: tandem repeat of two domains; 3 layers (a/b/a); parallel beta-sheet of 4 strands, order 2134
- HemD-like (69617)
duplication: consists of two similar 'swapped' domain with 3 layers (a/b/a) each; parallel beta-sheet of 5 strands, order 21345
- CAC2185-like (142794)
consists of two non-similar domains, 3 layers (a/b/a) each; d1 has parallel sheet of 4 strands, order 2134; d2 has parallel sheet of 5 strands, order 21345, and antiparallel meander sheet of 3 strands
- Periplasmic binding protein-like I (53821)
consists of two similar intertwined domain with 3 layers (a/b/a) each: duplication
parallel beta-sheet of 6 strands, order 213456
- Periplasmic binding protein-like II (53849)
consists of two similar intertwined domain with 3 layers (a/b/a) each: duplication
mixed beta-sheet of 5 strands, order 21354; strand 5 is antiparallel to the rest
- Thiolase-like (53900)
consists of two similar domains related by pseudo dyad; duplication
3 layers: a/b/a; mixed beta-sheet of 5 strands, order 32451; strand 5 is antiparallel to the rest
- NIF3 (NGG1p interacting factor 3)-like (102704)
consist of two intertwined domains; duplication: contains two structural repeats of alpha-beta-(beta-alpha)3 motif with mixed beta-sheet, order: 1432, strand 1 is antiparallel to the rest
- Fe-only hydrogenase (53919)
consist of two intertwined domains; contains partial duplication
- ComB-like (142822)
contains of two similar intertwined domains related by pseudo dyad; duplication; core: 3 layers: a/b/a; parallel beta-sheet of 4 strands, order 1423
- CoA-transferase family III (CaiB/BaiF) (89795)
consist of two different alpha/beta domains; N-terminal domain has a SurE-like topology with a left-handed beta-alpha-beta unit
- Cytidine deaminase-like (53926)
core: alpha-beta(2)-(alpha-beta)2; 3 layers (a/b/a); mixed beta-sheet of 4 strands, order 2134; strand 1 is antiparallel to the rest