Folds:

1. g.1: Insulin-like [56993] (1 superfamily) nearly all-alpha can be classified as disulfide-rich

2. g.2: Toxic hairpin [57006] (3 superfamilies) disulfide crosslinked alpha-helical hairpin

3. g.3: Knottins (small inhibitors, toxins, lectins) [57015] (19 superfamilies) disulfide-bound fold; contains beta-hairpin with two adjacent disulfides

4. g.4: PMP inhibitors [57282] (1 superfamily) disulfide-rich fold; all-beta: 3 antiparallel strands

5. g.5: Midkine [57287] (1 superfamily) disulfide-rich fold; all-beta: 3 antiparallel strands

6. g.6: Amb V allergen [57295] (1 superfamily) disulfide-rich; alpha+beta: 3 antiparallel strands followed by a short alpha helix

7. g.7: Snake toxin-like [57301] (1 superfamily) disulfide-rich fold: nearly all-beta

8. g.8: BPTI-like [57361] (1 superfamily) disulfide-rich alpha+beta fold

9. g.9: Defensin-like [57391] (1 superfamily) Disulfide-rich fold, nearly all-beta

10. g.10: Hairpin loop containing domain-like [57413] (1 superfamily) alpha+beta fold with two crossing loops

11. g.11: Neurotoxin III (ATX III) [57418] (1 superfamily) disulfide-rich fold

12. g.12: LDL receptor-like module [57423] (1 superfamily) disulfide-rich calcium-binding fold

13. g.13: Crambin-like [57428] (1 superfamily) disulfide-rich alpha+beta fold

14. g.14: Kringle-like [57439] (1 superfamily) disulfide-rich fold; nearly all-beta

15. g.16: Trefoil/Plexin domain-like [57491] (3 superfamilies) disulfide-rich fold; common core is alpha+beta with two conserved disulfides

16. g.17: Cystine-knot cytokines [57500] (1 superfamily) disulfide-rich fold; common core is all-beta

17. g.18: Complement control module/SCR domain [57534] (1 superfamily) disulfide-rich all-beta fold

18. g.19: Crisp domain-like [57545] (1 superfamily) disulfide-rich all-alpha fold

19. g.20: Blood coagulation inhibitor (disintegrin) [57551] (1 superfamily) small disulfide-rich

20. g.21: Methylamine dehydrogenase, L chain [57560] (1 superfamily) disulfide-rich; nearly all-beta

21. g.22: Serine protease inhibitors [57566] (1 superfamily) disulfide-rich; nearly all-beta

22. g.23: TB module/8-cys domain [57580] (1 superfamily) disulfide-rich; alpha+beta

23. g.24: TNF receptor-like [57585] (1 superfamily) duplication: consists of three similar disulfide-rich domains

24. g.25: Heparin-binding domain from vascular endothelial growth factor [57592] (1 superfamily) duplication: consists of two similar disulfide-rich domains, alpha+beta

25. g.26: Antifungal protein (AGAFP) [57597] (1 superfamily) disulfide-rich; all-beta: open barrel, 5 strands; OB-fold-like

26. g.27: FnI-like domain [57602] (1 superfamily) disulfide-rich, all-beta

27. g.28: Thyroglobulin type-1 domain [57609] (1 superfamily) disulfide-rich, alpha+beta

28. g.29: Type X cellulose binding domain, CBDX [57614] (1 superfamily) disulfide-rich, alpha+beta

29. g.30: Carboxypeptidase inhibitor [57619] (1 superfamily) disulfide-rich, alpha+beta

30. g.31: Invertebrate chitin-binding proteins [57624] (1 superfamily) disulfide-rich

31. g.32: GLA-domain [57629] (1 superfamily) Calcium ion-bound

32. g.33: Cholecystokinin A receptor, N-domain [57641] (1 superfamily) a few helical turns and a disulfide-crosslinked loop

33. g.34: HIV-1 VPU cytoplasmic domain [57646] (1 superfamily) a few helical turns assembled without a hydrophobic core?

34. g.35: HIPIP (high potential iron protein) [57651] (1 superfamily) folds around 4Fe-4S cluster

35. g.36: Ferredoxin thioredoxin reductase (FTR), catalytic beta chain [57661] (1 superfamily) folds around 4Fe-4S cluster

36. g.37: C2H2 and C2HC zinc fingers [57666] (1 superfamily) alpha+beta metal(zinc)-bound fold: beta-hairpin + alpha-helix

37. g.38: Zn2/Cys6 DNA-binding domain [57700] (1 superfamily) all-alpha dimetal(zinc)-bound fold

38. g.39: Glucocorticoid receptor-like (DNA-binding domain) [57715] (1 superfamily) alpha+beta metal(zinc)-bound fold

39. g.40: Retrovirus zinc finger-like domains [57755] (1 superfamily) metal(zinc)-bound fold

40. g.41: Rubredoxin-like [57769] (16 superfamilies) metal(zinc or iron)-bound fold; sequence contains two CX(n)C motifs, in most cases n = 2

41. g.42: Ribosomal protein L36 [57839] (1 superfamily) zinc-bound beta-ribbon motif

42. g.43: B-box zinc-binding domain [57844] (1 superfamily) zinc-bound alpha+beta motif

43. g.44: RING/U-box [57849] (1 superfamily) dimetal(zinc)-bound alpha+beta motif; structurally diverse

44. g.45: ArfGap/RecO-like zinc finger [57862] (1 superfamily) zinc-bound alpha+beta motif

45. g.46: Metallothionein [57867] (1 superfamily) metal(iron)-bound fold duplication: consists of clear structural/sequence repeats

46. g.47: Zinc domain conserved in yeast copper-regulated transcription factors [57878] (1 superfamily) metal(zinc)-bound alpha+beta fold

47. g.48: Ada DNA repair protein, N-terminal domain (N-Ada 10) [57883] (1 superfamily) metal(zinc)-bound alpha+beta fold

48. g.49: Cysteine-rich domain [57888] (1 superfamily) dimetal(zinc)-bound alpha+beta fold

49. g.50: FYVE/PHD zinc finger [57902] (1 superfamily) dimetal(zinc)-bound alpha+beta fold

50. g.51: Zn-binding domains of ADDBP [57916] (1 superfamily) metal(zinc)-bound alpha+beta fold

51. g.52: Inhibitor of apoptosis (IAP) repeat [57923] (1 superfamily) metal(zinc)-bound alpha+beta fold

52. g.53: TAZ domain [57932] (1 superfamily) all-alpha fold; Zn-binding sites are in the loops connecting helices

53. g.54: DnaJ/Hsp40 cysteine-rich domain [57937] (1 superfamily) metal(zinc)-bound extended beta-hairpin fold

54. g.55: Cellulose docking domain, dockering [64570] (1 superfamily) disulfide-rich, alpha+beta

55. g.58: Pheromone ER-23 [69963] (1 superfamily) disulfide-rich, all-alpha

56. g.59: Zinc-binding domain of translation initiation factor 2 beta [75688] (1 superfamily) zinc-bound beta-ribbon motif

57. g.60: TSP-1 type 1 repeat [82894] (1 superfamily) disulfide-rich fold; all-beta: 3 antiparallel strands

58. g.61: Apical membrane antigen 1 [82909] (1 superfamily) disulfide-rich, alpha+beta

59. g.62: Cysteine-rich DNA binding domain, (DM domain) [82926] (1 superfamily) alpha-helical fold with two Zn-binding sites

60. g.63: Mollusk pheromone [90182] (1 superfamily) disulfide-rich; all-alpha

61. g.64: Somatomedin B domain [90187] (1 superfamily) disulfide-rich

62. g.65: Notch domain [90192] (1 superfamily) disulfide-rich; all-alpha; calcium-binding

63. g.66: CCCH zinc finger [90228] (1 superfamily) metal(zinc)-bound alpha+beta fold

64. g.67: Zinc finger domain of DNA polymerase-alpha [90233] (1 superfamily) Zn-binding, all-alpha fold

65. g.68: Kazal-type serine protease inhibitors [100894] (1 superfamily)

66. g.69: Plant proteinase inhibitors [100896] (1 superfamily) disulfide-rich small alpha+beta fold; topological similarity to the Ovomucoid domain III

67. g.70: Necrosis inducing protein 1, NIP1 [103579] (1 superfamily) disulfide-rich fold; all-beta; duplication: contains two structural repeats

68. g.71: Mini-collagen I, C-terminal domain [103588] (1 superfamily) disulfide-rich

69. g.72: SBT domain [103611] (1 superfamily) consist of two different zn-binding subdomains, each subdomain resembles a distorted glucocorticoid receptor-like fold

70. g.73: CCHHC domain [103636] (1 superfamily) metal(zinc)-bound fold

71. g.74: Sec-C motif [103641] (1 superfamily) metal(zinc)-bound fold

72. g.75: TSP type-3 repeat [103646] (1 superfamily) metal(calcium)-bound fold

73. g.76: Hormone receptor domain [111417] (1 superfamily) disulfide-rich all-beta fold; contains beta sandwich of 5 strands

74. g.77: Resistin [111422] (1 superfamily) disulfide-rich six-stranded beta-sandwich; jelly-roll

75. g.78: YAP1 redox domain [111429] (1 superfamily) bipartite cysteine-rich all-alpha domain; a single helix in the N-terminal part (chain A) is linked by disulfides to the C-terminal part (chain B) [3-helical bundle of the RuvA C-terminal domain-like fold (scop_cf 46928)

76. g.79: WRKY DNA-binding domain [118289] (1 superfamily) zinc-bound 4-stranded meander beta-sheet, distinct from the beta-ribbon motifs

77. g.80: AN1-like Zinc finger [118309] (1 superfamily) dimetal(zinc)-bound alpha+beta fold; partial similarity to the Cysteine-rich domain fold (scop_cf 57888)

78. g.81: HSP33 redox switch-like [118351] (1 superfamily) alpha+beta zinc-binding domain; alpha(2)-beta(2)-alpha

79. g.82: Expressed protein At2g23090/F21P24.15 [118358] (1 superfamily) not assigned; partly disordered

80. g.83: Tim10-like [144121] (1 superfamily) alpha-hairpin crosslinked by two disulfides; assembles into a heterohexameric ring-like structure

81. g.84: Cysteine zipper [144128] (1 superfamily) string of helices that contain cysteines at almost every turn; folds upon itself and is crosslnked by multiple disulfides

82. g.85: HIT/MYND zinc finger-like [144231] (1 superfamily) dimetal(zinc)-bound alpha+beta fold; structural similarity to members of the Cysteine-rich domain fold (scop_cf 57888)

83. g.86: Coronavirus NSP10-like [144245] (1 superfamily) binds two zinc ion per subunit; forms a dodecameric shell

84. g.87: Viral leader polypeptide zinc finger [144250] (1 superfamily) consists of small beta-hairpin with CxH motif and short helix with CxxC motif

85. g.88: Intrinsically disordered proteins [144255] (1 superfamily) not a true fold

More info for Class g: Small proteins

Timeline for Class g: Small proteins:

• Class g: Small proteins first appeared (with stable ids) in SCOP 1.55
  
• Class g: Small proteins appears in SCOP 1.71
  
• Class g: Small proteins appears in SCOP 1.75
  
• Class g: Small proteins appears in the current release, SCOPe 2.08