Families of Proteolytic Enzymes

A family is a set of homologous proteolytic enzymes. The homology is shown by a significant similarity in amino acid sequence either to the type enzyme of the family, or to another protein that has already been shown to be homologous to the type enzyme, and thus a member of the family. The relationship must exist in the peptidase unit at least. A family can contain a single enzyme if no homologues are known, and a single gene product such as a virus polyprotein can contain more than one proteolytic enzyme each assigned to a different family. Each family is identified by a letter representing the catalytic type of the proteolytic enzymes it contains together with a unique number. Some families are divided into subfamilies because there is evidence of a very ancient divergence within the family, e.g. S1A, S1B.

Aspartic (A), Cysteine (C), Glutamic (G), Metallo (M), Asparagine (N), Mixed (P), Serine (S), Threonine (T), Unknown (U)

Aspartic (A) Peptidases
A1 A1A pepsin A (Homo sapiens)
A1B nepenthesin (Nepenthes gracilis)
A2 A2A HIV-1 retropepsin (human immunodeficiency virus 1)
A2B Ty3 transposon peptidase (Saccharomyces cerevisiae)
A2C Gypsy transposon peptidase (Drosophila melanogaster)
A2D Osvaldo retrotransposon peptidase (Drosophila buzzatii)
A3 A3A cauliflower mosaic virus-type peptidase (cauliflower mosaic virus)
A3B bacilliform virus peptidase (rice tungro bacilliform virus)
A5 thermopsin (Sulfolobus acidocaldarius)
A8 signal peptidase II (Escherichia coli)
A9 spumapepsin (human spumaretrovirus)
A11 A11A Copia transposon peptidase (Drosophila melanogaster)
A11B Ty1 transposon peptidase (Saccharomyces cerevisiae)
A22 A22A presenilin 1 (Homo sapiens)
A22B impas 1 peptidase (Homo sapiens)
A24 A24A type 4 prepilin peptidase 1 (Pseudomonas aeruginosa)
A24B FlaK peptidase (Methanococcus maripaludis)
A25 gpr peptidase (Bacillus megaterium)
A26 omptin (Escherichia coli)
A28 A28A DNA-damage inducible protein 1 (Saccharomyces cerevisiae)
A28B skin SASPase (Mus musculus)
A31 HybD peptidase (Escherichia coli)
A32 PerP peptidase (Caulobacter crescentus)
A36 sporulation factor SpoIIGA (Bacillus subtilis)
A37 sso1175 g.p. (Sulfolobus solfataricus)
Cysteine (C) Peptidases
C1 C1A papain (Carica papaya)
C1B bleomycin hydrolase (Saccharomyces cerevisiae)
C2 C2A calpain-2 (Homo sapiens)
C3 C3A poliovirus-type picornain 3C (human poliovirus 1)
C3B enterovirus picornain 2A (human poliovirus 1)
C3C foot-and-mouth disease virus picornain 3C (foot-and-mouth disease virus)
C3D cowpea mosaic comovirus-type picornain 3C (cowpea mosaic virus)
C3E hepatitis A virus-type picornain 3C (hepatitis A virus)
C3F parechovirus picornain 3C (human parechovirus 1)
C3G rice tungro spherical virus-type peptidase (rice tungro spherical virus)
C3H grapevine fanleaf-type nepovirus picornain 3C (grapevine fanleaf virus)
C4 nuclear-inclusion-a peptidase (plum pox virus)
C5 adenain (human adenovirus type 2)
C6 potato virus Y-type helper component peptidase (potato virus Y)
C7 chestnut blight fungus virus p29 peptidase (Cryphonectria hypovirus)
C8 chestnut blight fungus virus p48 peptidase (Cryphonectria hypovirus 1)
C9 sindbis virus-type nsP2 peptidase (Sindbis virus)
C10 streptopain (Streptococcus pyogenes)
C11 C11A clostripain (Clostridium histolyticum)
C11B PNT1 peptidase (Trypanosoma brucei)
C12 ubiquitinyl hydrolase-L1 (Homo sapiens)
C13 legumain (Canavalia ensiformis)
C14 C14A caspase-1 (Rattus norvegicus)
C14B metacaspase Yca1 (Saccharomyces cerevisiae)
C15 pyroglutamyl-peptidase I (Bacillus amyloliquefaciens)
C16 C16A murine hepatitis coronavirus papain-like peptidase 1 (murine hepatitis virus)
C16B mouse hepatitis coronavirus papain-like peptidase 2 (murine hepatitis virus)
C18 hepatitis C virus peptidase 2 (hepatitis C virus)
C19 ubiquitin-specific peptidase 14 (Homo sapiens)
C21 tymovirus peptidase (turnip yellow mosaic virus)
C23 carlavirus peptidase (apple stem pitting virus)
C24 rabbit hemorrhagic disease virus 3C-like peptidase (rabbit hemorrhagic disease virus)
C25 gingipain RgpA (Porphyromonas gingivalis)
C26 gamma-glutamyl hydrolase (Rattus norvegicus)
C27 rubella virus peptidase (Rubella virus)
C28 foot-and-mouth disease virus L-peptidase (foot-and-mouth disease virus)
C30 porcine transmissible gastroenteritis virus-type main peptidase (transmissible gastroenteritis virus)
C31 porcine reproductive and respiratory syndrome arterivirus-type cysteine peptidase alpha (lactate-dehydrogenase-elevating virus)
C32 equine arteritis virus-type cysteine peptidase (porcine reproductive and respiratory syndrome virus)
C33 equine arteritis virus Nsp2-type cysteine peptidase (equine arteritis virus)
C36 beet necrotic yellow vein furovirus-type papain-like peptidase (beet necrotic yellow vein virus)
C37 calicivirin (Southampton virus)
C39 bacteriocin-processing peptidase (Pediococcus acidilactici)
C40 dipeptidyl-peptidase VI (Lysinibacillus sphaericus)
C42 beet yellows virus-type papain-like peptidase (beet yellows virus)
C44 amidophosphoribosyltransferase precursor (Homo sapiens)
C45 acyl-coenzyme A:6-aminopenicillanic acid acyl-transferase precursor (Penicillium chrysogenum)
C46 hedgehog protein (Drosophila melanogaster)
C47 staphopain A (Staphylococcus aureus)
C48 Ulp1 peptidase (Saccharomyces cerevisiae)
C49 Strawberry mottle virus 3C-like peptidase (strawberry mottle virus)
C50 separase (Saccharomyces cerevisiae)
C51 D-alanyl-glycyl peptidase (Staphylococcus aureus)
C53 pestivirus Npro peptidase (classical swine fever virus)
C54 autophagin-1 (Homo sapiens)
C55 YopJ protein (Yersinia pseudotuberculosis)
C56 PfpI peptidase (Pyrococcus furiosus)
C57 vaccinia virus I7L processing peptidase (Vaccinia virus)
C58 C58A YopT peptidase (Yersinia pestis)
C58B HopN1 peptidase (Pseudomonas syringae)
C59 penicillin V acylase precursor (Lysinibacillus sphaericus)
C60 C60A sortase A (Staphylococcus aureus)
C60B sortase B (Staphylococcus aureus)
C62 gill-associated virus 3C-like peptidase (gill-associated virus)
C63 African swine fever virus processing peptidase (African swine fever virus)
C64 Cezanne peptidase (Homo sapiens)
C65 otubain-1 (Homo sapiens)
C66 IdeS peptidase (Streptococcus pyogenes)
C67 CylD peptidase (Homo sapiens)
C69 dipeptidase A (Lactobacillus helveticus)
C70 AvrRpt2 peptidase (Pseudomonas syringae)
C71 pseudomurein endoisopeptidase Pei (Methanobacterium phage psiM2)
C74 pestivirus NS2 peptidase (bovine viral diarrhea virus 1)
C75 AgrB peptidase (Staphylococcus aureus)
C76 viral tegument protein deubiquitinylating peptidase (human herpesvirus 1)
C78 C78A UfSP1 peptidase (Mus musculus)
C78B ZUP1 g.p. (Homo sapiens)
C79 ElaD peptidase (Escherichia coli)
C80 RTX self-cleaving toxin (Vibrio cholerae)
C82 C82A L,D-transpeptidase (Enterococcus faecium)
C82B ykuD transpeptidase (Bacillus subtilis)
C83 gamma-glutamylcysteine dipeptidyltranspeptidase (Nostoc sp. PCC 7120)
C84 prtH peptidase (Tannerella forsythia)
C85 C85A OTUD5 peptidase (Homo sapiens)
C85B OTU1 peptidase (Saccharomyces cerevisiae)
C86 ataxin-3 (Homo sapiens)
C87 nairovirus deubiquitinylating peptidase (Crimean-Congo hemorrhagic fever virus)
C89 acid ceramidase precursor (Homo sapiens)
C93 LapG peptidase (Pseudomonas fluorescens)
C95 lysosomal 66.3 kDa protein (Mus musculus)
C96 McjB peptidase (Escherichia coli)
C97 desumoylating isopeptidase 1 (Mus musculus)
C98 USPL1 peptidase (Homo sapiens)
C99 iflavirus processing peptidase (Ectropis obliqua picorna-like virus)
C100 agglutinin peptidase (Marasmius oreades)
C101 OTULIN peptidase (Homo sapiens)
C102 GtgE peptidase (Salmonella enterica)
C103 HopX1 peptidase } (Pseudomonas syringae)
C105 papain-like peptidase 1 alpha (simian hemorrhagic fever virus)
C106 archaeosortase A (Haloferax volcanii)
C108 Prp peptidase (Staphylococcus aureus)
C110 kyphoscoliosis peptidase (Mus musculus)
C111 coagulation factor XIIIa (Homo sapiens)
C113 IgdE peptidase (Streptococcus suis)
C115 MINDY-1 protein (Homo sapiens)
C116 dermonecrotic toxin (Pasteurella multocida)
C117 SpvD g.p. (Salmonella typhimurium)
C118 EspL g.p. (Escherichia coli)
C119 LotA g.p. (Legionella pneumophila)
C121 MINDY-4 peptidase (Homo sapiens)
C122 SdeA (Legionella pneumophila)
C123 RARP2 (Rickettsia rickettsii)
C124 Lem27 (Legionella pneumophila)
Glutamic (G) Peptidases
G1 scytalidoglutamic peptidase (Scytalidium lignicolum)
G2 pre-neck appendage protein (bacteriophage phi-29)
G3 strawberry mottle virus glutamic peptidase (strawberry mottle virus)
G4 Tiki1 peptidase (Homo sapiens)
G5 RCE1 peptidase (Saccharomyces cerevisiae)
G6 Ras/Rap1-specific peptidase (Vibrio vulnificus)
Metallo (M) Peptidases
M1 aminopeptidase N (Homo sapiens)
M2 angiotensin-converting enzyme peptidase unit 1 (Homo sapiens)
M3 M3A thimet oligopeptidase (Rattus norvegicus)
M3B oligopeptidase F (Lactococcus lactis)
M3C Pz-peptidase A (Geobacillus sp. MO-1)
M4 thermolysin (Bacillus thermoproteolyticus)
M5 mycolysin (Streptomyces cacaoi)
M6 immune inhibitor A peptidase (Bacillus thuringiensis)
M7 snapalysin (Streptomyces lividans)
M8 leishmanolysin (Leishmania major)
M9 M9A collagenase V (Vibrio alginolyticus)
M9B bacterial collagenase H (Clostridium histolyticum)
M10 M10A matrix metallopeptidase-1 (Homo sapiens)
M10B serralysin (Serratia marcescens)
M10C fragilysin (Bacteroides fragilis)
M11 gametolysin (Chlamydomonas reinhardtii)
M12 M12A astacin (Astacus astacus)
M12B adamalysin (Crotalus adamanteus)
M13 neprilysin (Homo sapiens)
M14 M14A carboxypeptidase A1 (Homo sapiens)
M14B carboxypeptidase E (Bos taurus)
M14C gamma-D-glutamyl--meso-diaminopimelate peptidase I (Lysinibacillus sphaericus)
M14D cytosolic carboxypeptidase 6 (Homo sapiens)
M15 M15A zinc D-Ala-D-Ala carboxypeptidase (Streptomyces albus)
M15B vanY D-Ala-D-Ala carboxypeptidase (Enterococcus faecium)
M15C Ply118 L-Ala-D-Glu peptidase (bacteriophage A118)
M15D vanX D-Ala-D-Ala dipeptidase (Enterococcus faecium)
M16 M16A pitrilysin (Escherichia coli)
M16B mitochondrial processing peptidase beta-subunit (Saccharomyces cerevisiae)
M16C eupitrilysin (Homo sapiens)
M17 leucyl aminopeptidase 3 (Bos taurus)
M18 aminopeptidase I (Saccharomyces cerevisiae)
M19 membrane dipeptidase (Homo sapiens)
M20 M20A glutamate carboxypeptidase (Pseudomonas sp.)
M20B peptidase T (Escherichia coli)
M20C Xaa-His dipeptidase (Escherichia coli)
M20D carboxypeptidase Ss1 (Sulfolobus solfataricus)
M20F carnosine dipeptidase II (Mus musculus)
M23 M23A beta-lytic metallopeptidase (Achromobacter lyticus)
M23B lysostaphin (Staphylococcus simulans)
M24 M24A methionyl aminopeptidase 1 (Escherichia coli)
M24B aminopeptidase P (Escherichia coli)
M26 IgA1-specific metallopeptidase (Streptococcus sanguinis)
M27 tentoxilysin (Clostridium tetani)
M28 M28A aminopeptidase S (Streptomyces griseus)
M28B glutamate carboxypeptidase II (Homo sapiens)
M28C IAP aminopeptidase (Escherichia coli)
M28D aminopeptidase ES-62 (Acanthocheilonema viteae)
M28E aminopeptidase Ap1 (Vibrio proteolyticus)
M28F YwaD peptidase (Bacillus subtilis)
M29 aminopeptidase T (Thermus aquaticus)
M30 hyicolysin (Staphylococcus hyicus)
M32 carboxypeptidase Taq (Thermus aquaticus)
M34 anthrax lethal factor (Bacillus anthracis)
M35 deuterolysin (Aspergillus flavus)
M36 fungalysin (Aspergillus fumigatus)
M38 isoaspartyl dipeptidase (Escherichia coli)
M41 FtsH peptidase (Escherichia coli)
M42 glutamyl aminopeptidase (Lactococcus lactis)
M43 M43A cytophagalysin (Cytophaga sp.)
M43B pappalysin-1 (Homo sapiens)
M44 pox virus metallopeptidase (Vaccinia virus)
M48 M48A Ste24 peptidase (Saccharomyces cerevisiae)
M48B HtpX peptidase (Escherichia coli)
M48C Oma1 peptidase (Saccharomyces cerevisiae)
M49 dipeptidyl-peptidase III (Rattus norvegicus)
M50 M50A site 2 peptidase (Homo sapiens)
M50B sporulation factor SpoIVFB (Bacillus subtilis)
M54 archaelysin (Methanocaldococcus jannaschii)
M55 D-aminopeptidase DppA (Bacillus subtilis)
M56 BlaR1 peptidase (Staphylococcus aureus)
M57 prtB g.p. (Myxococcus xanthus)
M60 enhancin (Lymantria dispar nucleopolyhedrovirus)
M61 glycyl aminopeptidase (Sphingomonas capsulata)
M64 IgA peptidase (Clostridium ramosum)
M66 StcE peptidase (Escherichia coli)
M67 M67A PSMD14 peptidase (Saccharomyces cerevisiae)
M67B JAMM-like protein (Archaeoglobus fulgidus)
M67C STAMBP isopeptidase (Homo sapiens)
M72 peptidyl-Asp metallopeptidase (Pseudomonas aeruginosa)
M73 camelysin (Bacillus cereus)
M74 murein endopeptidase (Escherichia coli)
M75 imelysin (Pseudomonas aeruginosa)
M76 Atp23 peptidase (Homo sapiens)
M77 tryptophanyl aminopeptidase 7-DMATS-type peptidase (Aspergillus fumigatus)
M78 ImmA peptidase (Bacillus subtilis)
M80 Wss1 peptidase (Saccharomyces cerevisiae)
M81 microcystinase MlrC (Sphingomonas sp. ACM-3962)
M82 PrsW peptidase (Bacillus subtilis)
M84 MpriBi peptidase (Bacillus intermedius)
M85 NleC peptidase (Escherichia coli)
M86 PghP gamma-polyglutamate hydrolase (Bacillus phage phiNIT1)
M87 chloride channel accessory protein 1 (Homo sapiens)
M88 IMPa peptidase (Pseudomonas aeruginosa)
M90 MtfA peptidase (Escherichia coli)
M91 NleD peptidase (Escherichia coli)
M93 BACCAC_01431 g.p. and similar (Bacteroides caccae)
M95 abylysin (Pyrococcus abyssi)
M97 EcxAB peptidase (Escherichia coli)
M98 YghJ g.p. (Escherichia coli)
M99 Csd4 peptidase (Helicobacter pylori)
M100 spartan peptidase (Homo sapiens)
M102 DA1 peptidase (Arabidopsis thaliana)
M103 TldD peptidase (Escherichia coli)
M105 MAP1 peptidase (Myxococcus xanthus)
M106 FP0506 g.p. (Flavobacterium psychrophilum)
Asparagine (N) Peptide Lyases
N1 nodavirus peptide lyase (flock house virus)
N2 tetravirus coat protein (Nudaurelia capensis omega virus)
N4 Tsh-associated self-cleaving domain and similar (Escherichia coli)
N5 picobirnavirus self-cleaving protein (Human picobirnavirus)
N6 YscU protein (Yersinia pseudotuberculosis)
N7 reovirus type 1 coat protein (Mammalian orthoreovirus 1)
N8 poliovirus capsid VP0-type self-cleaving protein (human poliovirus 1)
N9 intein-containing V-type proton ATPase catalytic subunit A (Saccharomyces cerevisiae)
N10 intein-containing replicative DNA helicase precursor (Synechocystis sp. PCC 6803)
N11 intein-containing chloroplast ATP-dependent peptide lyase (Chlamydomonas eugametos)
Mixed (P) Peptidases
P1 DmpA aminopeptidase (Ochrobactrum anthropi)
P2 P2A EGF-like module containing mucin-like hormone receptor-like 2 (Homo sapiens)
P2B polycystin-1 (Homo sapiens)
Serine (S) Peptidases
S1 S1A chymotrypsin A (Bos taurus)
S1B glutamyl endopeptidase I (Staphylococcus aureus)
S1C DegP peptidase (Escherichia coli)
S1D lysyl endopeptidase (Achromobacter lyticus)
S1E streptogrisin A (Streptomyces griseus)
S3 togavirin (Sindbis virus)
S6 IgA1-specific serine peptidase (Neisseria gonorrhoeae)
S7 flavivirin (yellow fever virus)
S8 S8A subtilisin Carlsberg (Bacillus licheniformis)
S8B kexin (Saccharomyces cerevisiae)
S9 S9A prolyl oligopeptidase (Sus scrofa)
S9B dipeptidyl-peptidase IV (Homo sapiens)
S9C acylaminoacyl-peptidase (Homo sapiens)
S9D glutamyl endopeptidase C (Arabidopsis thaliana)
S10 carboxypeptidase Y (Saccharomyces cerevisiae)
S11 D-Ala-D-Ala carboxypeptidase A (Geobacillus stearothermophilus)
S12 D-Ala-D-Ala carboxypeptidase B (Streptomyces lividans)
S13 D-Ala-D-Ala peptidase C (Escherichia coli)
S14 peptidase Clp (Escherichia coli)
S15 Xaa-Pro dipeptidyl-peptidase (Lactococcus lactis)
S16 Lon-A peptidase (Escherichia coli)
S21 cytomegalovirus assemblin (human herpesvirus 5)
S24 repressor LexA (Escherichia coli)
S26 S26A signal peptidase I (Escherichia coli)
S26B signalase 21 kDa component (Saccharomyces cerevisiae)
S26C TraF peptidase (Escherichia coli)
S28 lysosomal Pro-Xaa carboxypeptidase (Homo sapiens)
S29 hepacivirin (hepatitis C virus)
S30 potyvirus P1 peptidase (plum pox virus)
S31 pestivirus NS3 polyprotein peptidase (bovine viral diarrhea virus 1)
S32 equine arteritis virus serine peptidase (equine arteritis virus)
S33 prolyl aminopeptidase (Neisseria gonorrhoeae)
S37 PS-10 peptidase (Streptomyces lividans)
S39 S39A sobemovirus peptidase (cocksfoot mottle virus)
S39B luteovirus peptidase (potato leaf roll luteovirus)
S41 S41A C-terminal processing peptidase-1 (Escherichia coli)
S41B tricorn core peptidase (Thermoplasma acidophilum)
S45 penicillin G acylase precursor (Escherichia coli)
S46 dipeptidyl-peptidase 7 (Porphyromonas gingivalis)
S48 HetR putative peptidase (Anabaena variabilis)
S49 S49A signal peptide peptidase A (Escherichia coli)
S49B protein C (bacteriophage lambda)
S49C archaean signal peptide peptidase 1 (Pyrococcus horikoshii)
S50 infectious pancreatic necrosis birnavirus Vp4 peptidase (infectious pancreatic necrosis virus)
S51 dipeptidase E (Escherichia coli)
S53 sedolisin (Pseudomonas sp. 101)
S54 rhomboid-1 (Drosophila melanogaster)
S55 SpoIVB peptidase (Bacillus subtilis)
S59 nucleoporin 145 (Homo sapiens)
S60 lactoferrin (Homo sapiens)
S62 influenza A PA peptidase (influenza A virus)
S64 Ssy5 peptidase (Saccharomyces cerevisiae)
S65 picornain-like serine peptidase (Breda virus)
S66 murein tetrapeptidase LD-carboxypeptidase (Pseudomonas aeruginosa)
S68 PIDD auto-processing protein unit 1 (Homo sapiens)
S69 Tellina virus 1 VP4 peptidase (Tellina virus 1)
S71 MUC1 self-cleaving mucin (Homo sapiens)
S72 dystroglycan (Homo sapiens)
S73 gpO peptidase (Enterobacteria phage P2)
S74 Escherichia coli phage K1F endosialidase CIMCD self-cleaving protein (Enterobacteria phage K1F)
S75 White bream virus serine peptidase (White bream virus)
S77 prohead peptidase gp21 (Enterobacteria phage T4)
S78 prohead peptidase (Enterobacteria phage HK97)
S79 CARD8 self-cleaving protein (Homo sapiens)
S80 prohead peptidase gp175 (Pseudomonas phage phiKZ)
S81 destabilase (Hirudo medicinalis)
S82 autocrine proliferation repressor protein A (Dictyostelium discoideum)
S85 small protease (Pseudomonas aeruginosa)
Threonine (T) Peptidases
T1 T1A archaean proteasome, beta component (Thermoplasma acidophilum)
T1B HslV component of HslUV peptidase (Escherichia coli)
T2 glycosylasparaginase precursor (Homo sapiens)
T3 gamma-glutamyltransferase 1 (Escherichia coli)
T5 ornithine acetyltransferase precursor (Saccharomyces cerevisiae)
T7 CwpV self-cleaving threonine peptidase (Clostridium difficile)
T8 HopB1 g.p. (Pseudomonas syringae)
Peptidases of Unknown Catalytic Type
U32 collagenase (Porphyromonas gingivalis)
U40 protein P5 murein endopeptidase (bacteriophage phi-6)
U49 Lit peptidase (Escherichia coli)
U56 homomultimeric peptidase (Thermotoga maritima)
U57 yabG protein (Bacillus subtilis)
U69 AIDA-I self-cleaving autotransporter protein (Escherichia coli)
U72 Dop isopeptidase (Mycobacterium tuberculosis)