| PF00148 | Oxidored_nitro | Nitrogenase component 1 type Oxidoreductase | C1DGZ8 |
| PF00174 | Oxidored_molyb | Oxidoreductase molybdopterin binding domain | A0A3Q0L063 |
| PF00185 | OTCace | Aspartate/ornithine carbamoyltransferase, Asp/Orn binding domain | P0A786 |
| PF00213 | OSCP | ATP synthase delta (OSCP) subunit | A0R203 |
| PF00215 | OMPdecase | Orotidine 5'-phosphate decarboxylase / HUMPS family | A0A0M3H420 |
| PF00278 | Orn_DAP_Arg_deC | Pyridoxal-dependent decarboxylase, C-terminal sheet domain | Q8ZNC4 |
| PF00420 | Oxidored_q2 | NADH-ubiquinone/plastoquinone oxidoreductase chain 4L | A0QU26 |
| PF00499 | Oxidored_q3 | NADH-ubiquinone/plastoquinone oxidoreductase chain 6 | A0QU27 |
| PF00507 | Oxidored_q4 | NADH-ubiquinone/plastoquinone oxidoreductase, chain 3 | A0QU36 |
| PF00691 | OmpA | OmpA family | A0A422WJQ0 |
| PF00724 | Oxidored_FMN | NADH:flavin oxidoreductase / NADH oxidase family | Q9FEW9 |
| PF00865 | Osteopontin | Osteopontin | |
| PF01058 | Oxidored_q6 | NADH ubiquinone oxidoreductase, 20 Kd subunit | A0QU35 |
| PF01059 | Oxidored_q5_N | NADH-ubiquinone oxidoreductase chain 4, amino terminus | P18931 |
| PF01103 | Omp85 | Omp85 superfamily domain | P0A940 |
| PF01160 | Opiods_neuropep | Vertebrate endogenous opioids neuropeptide | |
| PF01237 | Oxysterol_BP | Oxysterol-binding protein | P22059 |
| PF01276 | OKR_DC_1 | Orn/Lys/Arg decarboxylase, major domain | A0A379GV98 |
| PF01277 | Oleosin | Oleosin | |
| PF01278 | Omptin | Omptin family | P17811 |
| PF01385 | OrfB_IS605 | Probable transposase | |
| PF01389 | OmpA_membrane | OmpA-like transmembrane domain | P0A910 |
| PF01700 | Orbi_VP3 | Orbivirus VP3 (T2) protein | Q1AE73 |
| PF01796 | OB_ChsH2_C | ChsH2, C-terminal OB-fold domain | Q39VG2 |
| PF01901 | O_anti_polymase | Putative O-antigen polymerase | |
| PF02072 | Orexin | Prepro-orexin | |
| PF02100 | ODC_AZ | Ornithine decarboxylase antizyme | P54368 |
| PF02101 | Ocular_alb | Ocular albinism type 1 protein | |
| PF02159 | Oest_recep | Oestrogen receptor | |
| PF02191 | OLF | Olfactomedin-like domain | Q80TS3 |
| PF02317 | Octopine_DH | NAD/NADP octopine/nopaline dehydrogenase, alpha-helical domain | Q9BHM6 |
| PF02321 | OEP | Outer membrane efflux protein | A0A1C3Q001 |
| PF02338 | OTU | OTU-like cysteine protease | P38747 |
| PF02423 | OCD_Mu_crystall | Ornithine cyclodeaminase/mu-crystallin family | B7FJU0 |
| PF02462 | Opacity | Opacity family porin protein | Q04884 |
| PF02471 | OspE | Borrelia outer surface protein E | Q45001 |
| PF02566 | OsmC | OsmC-like protein | Q3JK82 |
| PF02729 | OTCace_N | Aspartate/ornithine carbamoyltransferase, carbamoyl-P binding domain | P0A786 |
| PF02784 | Orn_Arg_deC_N | Pyridoxal-dependent decarboxylase, pyridoxal binding domain | Q8ZNC4 |
| PF03137 | OATP | Organic Anion Transporter Polypeptide (OATP) family | Q8C0X7 |
| PF03169 | OPT | OPT oligopeptide transporter protein | Q2PGC4 |
| PF03189 | Otopetrin | Otopetrin | A9JTM7 |
| PF03207 | OspD | Borrelia outer surface protein D (OspD) | |
| PF03345 | OST48_N | OST48, N-terminal domain | P39656 |
| PF03373 | Octapeptide | Octapeptide repeat | |
| PF03392 | OS-D | Insect pheromone-binding family, A10/OS-D | A0A0P0EUM0 |
| PF03532 | OMS28_porin | OMS28 porin | |
| PF03573 | OprD | outer membrane porin, OprD family | A0A0P0QBS3 |
| PF03709 | OKR_DC_1_N | Orn/Lys/Arg decarboxylase, N-terminal domain | A0A379GV98 |
| PF03711 | OKR_DC_1_C | Orn/Lys/Arg decarboxylase, C-terminal domain | A0A379GV98 |
| PF03826 | OAR | OAR motif | |
| PF03827 | Orexin_rec2 | Orexin receptor type 2 | O43614 |
| PF03922 | OmpW | OmpW family | Q00595 |
| PF03938 | OmpH | Outer membrane protein (OmpH-like) | Q9A712 |
| PF03977 | OAD_beta | Na+-transporting oxaloacetate decarboxylase beta subunit | Q8ZRY4 |
| PF04061 | ORMDL | ORMDL family | Q8N138 |
| PF04069 | OpuAC | Substrate binding domain of ABC-type glycine betaine transport system | B6JM49 |
| PF04277 | OAD_gamma | Oxaloacetate decarboxylase, gamma chain | Q03032 |
| PF04606 | Ogr_Delta | Ogr/Delta-like zinc finger | |
| PF04664 | OGFr_N | Opioid growth factor receptor (OGFr) conserved region | |
| PF04680 | OGFr_III | Opioid growth factor receptor disordered repeat | |
| PF04756 | OST3_OST6 | OST3 / OST6 family, transporter family | Q9NRP0 |
| PF04844 | Ovate | Transcriptional repressor, ovate | |
| PF04966 | OprB | Carbohydrate-selective porin, OprB family | A5VZA8 |
| PF05005 | Ocnus | Janus/Ocnus family (Ocnus) | Q9NRX4 |
| PF05251 | Ost5 | Oligosaccharyltransferase subunit 5 | P61165 |
| PF05460 | ORC6 | Origin recognition complex subunit 6 (ORC6) | P38826 |
| PF05736 | OprF | OprF membrane domain | P13794 |
| PF05788 | Orbi_VP1 | Orbivirus RNA-dependent RNA polymerase (VP1) | W0G557 |
| PF05813 | Orthopox_F7 | Orthopoxvirus F7 protein | |
| PF06024 | Orf78 | Orf78 (ac78) | |
| PF06334 | Orthopox_A47 | Orthopoxvirus A47 protein | |
| PF06357 | Omega-toxin | Omega-atracotoxin | P56207 |
| PF06554 | Olfactory_mark | Olfactory marker protein | P08523 |
| PF06758 | Olduvai | Olduvai domain | |
| PF07034 | ORC3_N | Origin recognition complex (ORC) subunit 3 N-terminus | Q9UBD5 |
| PF07047 | OPA3 | Optic atrophy 3 protein (OPA3) | |
| PF07051 | OCIA | Ovarian carcinoma immunoreactive antigen (OCIA) | |
| PF07175 | Osteoregulin | Osteoregulin | |
| PF07204 | Orthoreo_P10 | Orthoreovirus membrane fusion protein p10 | |
| PF07239 | OpcA | Outer membrane protein OpcA | Q9AE79 |
| PF07303 | Occludin_ELL | Occludin homology domain | O00472 |
| PF07717 | OB_NTP_bind | Oligonucleotide/oligosaccharide-binding (OB)-fold | O43143 |
| PF07764 | Omega_Repress | Omega Transcriptional Repressor | Q57468 |
| PF07856 | Orai-1 | Mediator of CRAC channel activity | Q9U6B8 |
| PF07934 | OGG_N | 8-oxoguanine DNA glycosylase, N-terminal domain | O08760 |
| PF08035 | Op_neuropeptide | Opioids neuropeptide | P01189 |
| PF08206 | OB_RNB | Ribonuclease B OB domain | P30850 |
| PF08352 | oligo_HPY | Oligopeptide/dipeptide transporter, C-terminal region | Q8RDH4 |
| PF08525 | OapA_N | Opacity-associated protein A N-terminal motif | |
| PF08618 | Opi1 | Transcription factor Opi1 | |
| PF08635 | ox_reductase_C | Putative oxidoreductase C terminal domain | |
| PF08684 | ocr | DNA mimic ocr | P03775 |
| PF08946 | Osmo_CC | Osmosensory transporter coiled coil | P0C0L7 |
| PF09253 | Ole_e_6 | Pollen allergen Ole e 6 | O24172 |
| PF09349 | OHCU_decarbox | OHCU decarboxylase | B7GAW6 |
| PF09463 | Opy2 | Opy2 protein | |
| PF09482 | OrgA_MxiK | Bacterial type III secretion apparatus protein (OrgA_MxiK) | |
| PF09488 | Osmo_MPGsynth | Mannosyl-3-phosphoglycerate synthase (osmo_MPGsynth) | O58689 |
| PF09777 | OSTMP1 | Osteopetrosis-associated transmembrane protein 1 precursor | Q86WC4 |
| PF09791 | Oxidored-like | Oxidoreductase-like protein, N-terminal | G0S982 |
| PF09845 | OapC | Origin-associated protein OapC | |
| PF09846 | OapB | Origin-associated protein OapB | |
| PF09859 | Oxygenase-NA | Oxygenase, catalysing oxidative methylation of damaged DNA | |
| PF10128 | OpcA_G6PD_assem | Glucose-6-phosphate dehydrogenase subunit N-terminal domain | |
| PF10129 | OpgC_C | OpgC protein | |
| PF10188 | Oscp1 | Organic solute transport protein 1 | |
| PF10215 | Ost4 | Oligosaccaryltransferase | P0C6T2 |
| PF10250 | O-FucT | GDP-fucose protein O-fucosyltransferase | Q8WR51 |
| PF10421 | OAS1_C | 2'-5'-oligoadenylate synthetase 1, domain 2, C-terminus | Q15646 |
| PF10543 | ORF6N | ORF6N domain | |
| PF10549 | ORF11CD3 | ORF11CD3 domain | |
| PF10552 | ORF6C | ORF6C domain | |
| PF10637 | Ofd1_CTDD | Oxoglutarate and iron-dependent oxygenase degradation C-term | Q11120 |
| PF10717 | ODV-E18 | Occlusion-derived virus envelope protein ODV-E18 | |
| PF10950 | Organ_specific | Organ specific protein | |
| PF11078 | Optomotor-blind | Optomotor-blind protein N-terminal region | |
| PF11551 | Omp28 | Outer membrane protein Omp28 | Q9S3Q1 |
| PF11557 | Omp_AT | Solitary outer membrane autotransporter beta-barrel domain | |
| PF12013 | OrsD | Orsellinic acid/F9775 biosynthesis cluster protein D | |
| PF12202 | OSR1_C | Oxidative-stress-responsive kinase 1 C-terminal domain | Q9BYP7 |
| PF12573 | OxoDH_E1alpha_N | 2-oxoisovalerate dehydrogenase E1 alpha subunit N terminal | P09060 |
| PF12872 | OST-HTH | OST-HTH/LOTUS domain | P25158 |
| PF12911 | OppC_N | N-terminal TM domain of oligopeptide transport permease C | |
| PF13100 | OstA_2 | OstA-like protein | |
| PF13376 | OmdA | Bacteriocin-protection, YdeI or OmpD-Associated | |
| PF13425 | O-antigen_lig | O-antigen ligase like membrane protein | |
| PF13505 | OMP_b-brl | Outer membrane protein beta-barrel domain | A0A5P8YI02 |
| PF13568 | OMP_b-brl_2 | Outer membrane protein beta-barrel domain | |
| PF14296 | O-ag_pol_Wzy | O-antigen polysaccharide polymerase Wzy | |
| PF14418 | OHA | OST-HTH Associated domain | |
| PF14441 | OTT_1508_deam | OTT_1508-like deaminase | |
| PF14629 | ORC4_C | Origin recognition complex (ORC) subunit 4 C-terminus | P54791 |
| PF14630 | ORC5_C | Origin recognition complex (ORC) subunit 5 C-terminus | P50874 |
| PF14778 | ODR4-like | Odorant response abnormal 4-like | |
| PF14905 | OMP_b-brl_3 | Outer membrane protein beta-barrel family | |
| PF14941 | OAF_N | Out at first | |
| PF15048 | OSTbeta | Organic solute transporter subunit beta protein | |
| PF15182 | OTOS | Otospiralin | |
| PF15424 | ODAM | Odontogenic ameloblast-associated family | |
| PF15506 | OCC1 | OCC1 family | |
| PF15680 | OFCC1 | Orofacial cleft 1 candidate gene 1 protein | |
| PF15848 | ODAPH | Odontogenesis associated phosphoprotein | |
| PF16312 | Oberon_cc | Coiled-coil region of Oberon | |
| PF16490 | Oxidoreduct_C | Putative oxidoreductase C terminal domain | A7ABT3 |
| PF16552 | OAM_alpha | D-ornithine 4,5-aminomutase alpha-subunit | E3PY96 |
| PF16554 | OAM_dimer | Dimerisation domain of d-ornithine 4,5-aminomutase | E3PY95 |
| PF16726 | OCRL_clath_bd | Inositol polyphosphate 5-phosphatase clathrin binding domain | Q01968 |
| PF16870 | OxoGdeHyase_C | 2-oxoglutarate dehydrogenase C-terminal | Q02218 |
| PF16955 | OFeT_1 | Ferrous iron uptake permease, iron-lead transporter | |
| PF16961 | OmpA_like | Putative OmpA-OmpF-like porin family | |
| PF17062 | Osw5 | Outer spore wall 5 | |
| PF17182 | OSK | OSK domain | P25158 |
| PF17304 | OM14_C | Mitochondrial outer membrane protein OM14, C-terminal | |
| PF17780 | OCRE | OCRE domain | P52756 |
| PF17849 | OB_Dis3 | Dis3-like cold-shock domain 2 (CSD2) | Q8IYB7 |
| PF17912 | OB_MalK | MalK OB fold domain | A3DGK4 |
| PF18042 | ORF_12_N | ORF 12 gene product N-terminal | Q8KRB7 |
| PF18137 | ORC_WH_C | Origin recognition complex winged helix C-terminal | P54790 |
| PF18235 | OST_P2 | Oligosaccharyltransferase Peripheral 2 domain | I6V0B8 |
| PF18246 | OST_IS | Oligosaccharyltransferase Insert domain | I6V0B8 |
| PF18492 | ORF_2_N | Open reading frame 2 N-terminal domain | W5JXD7 |
| PF18589 | ObR_Ig | Obesity receptor immunoglobulin like domain | P48357 |
| PF19143 | Omp85_2 | OMP85 superfamily | |
| PF19434 | OPA1_C | Dynamin-like GTPase OPA1 C-terminal | |
| PF19583 | ODP | ODP family beta lactamase | Q9S5W7 |
| PF19675 | ORC3_ins | Origin recognition complex subunit 3 insertion domain | Q9UBD5 |
| PF19858 | OxRdtase_C | Bacterial oxidoreductases, C-terminal | |
| PF20171 | OpcA_G6PD_C | Glucose-6-phosphate dehydrogenase subunit C-terminal domain | |
| PF20469 | OLD-like_TOPRIM | Overcoming lysogenization defect protein-like, TOPRIM domain | E8PLM2 |
| PF20913 | ObcA_N | Oxalate Biosynthetic Component A, N-terminal domain | |
| PF21310 | OCRL-like_ASH | Inositol polyphosphate 5-phosphatase OCRL-like, ASH domain | |
| PF21312 | ORC1_wHTH | Origin recognition complex subunit 1 C-terminal winged HTH domain | |
| PF21403 | OTU1_UBXL | OTU1, UBXL domain | |
| PF21498 | Obc1_C | Oxalate biosynthetic component 1, C-terminal | |
| PF21502 | Obc1_cap | Oxalate biosynthetic component 1, cap domain | |
| PF21618 | OST_P1 | Oligosaccharyl transferase, Peripheral 1 domain | |
| PF21639 | ORC5_lid | ORC5, lid domain | |
| PF21773 | ODAD1_CC | ODAD1 central coiled coil region | |
| PF21790 | OGG | Putative 8-oxoguanine DNA glycosylase OGG-like protein | |
| PF21913 | ORC6_2nd | ORC6 second cyclin-like domain | |
| PF22010 | OrtA | AKP thiolase subunit OrtA | |
| PF22015 | OSBS_N | O-succinylbenzoate synthase, N-terminal domain | |
| PF22112 | OmcA-like_N | OmcA-like N-terminal domain | |
| PF22175 | Ogg-HhH | 8-oxoguanine DNA glycosylase | |
| PF22303 | OspG_kinase | Protein kinase OspG, kinase domain | |
| PF22413 | OGT_N | Methylated DNA-protein cysteine MeTransferase OGT N-terminal domain | |
| PF22620 | OYE-like_second_a-b | OYE-like second alpha/beta domain | |
| PF22651 | OBP47_like | AgamOBP47-like | |
| PF22779 | OB_SHLD2_2nd | Shieldin complex subunit 2, second OB fold domain | |
| PF22873 | OAF_C | Out at first, C-terminal | |
| PF22896 | OB_RNR_1st | Ribonuclease R, OB first domain, N-terminal | |
| PF23139 | OB_YrrC | ATP-dependent DNA helicase YrrC, OB-fold domain | |
| PF23358 | OST48_MD | OST48 middle domain | |
| PF24190 | OB_RNR_2nd | Ribonuclease R second OB domain | |
| PF24339 | OB_DEPS-1_3rd | P-granule-associated protein DEPS-1, third OB-fold domain | |
| PF24341 | OB_DEPS-1_6th | P-granule-associated protein DEPS-1, sixth OB-fold domain | |
| PF24342 | OB_DEPS-1_2nd | P-granule-associated protein DEPS-1, second OB-fold domain | |
| PF24343 | OB_DEPS-1_1st | P-granule-associated protein DEPS-1, first OB-fold domain | |
| PF24389 | ORC-CDC6-like | ORC-CDC6-like | |
| PF24395 | OLD-like_TOPRIM_1 | OLD-like TOPRIM 1 | |
| PF24423 | OVT1 | Major antigen, helical domain | |
| PF24682 | OB_RRP5 | RRP5 OB-fold domain | |
| PF24685 | OB_RRP5_4th | RRP5 OB-fold domain | |
| PF24687 | OrgC | Type III Secretion system protein OrgC | |