porin family protein is a member of a large superfamily consisting of classical (gram-negative ) porins which are non-specific channels for small hydrophillic molecules, maltoporin-like channels which have specificities for various sugars, and ligand-gated protein channels which cooperate with a TonB associated inner membrane complex to actively transport ligands via the proton motive force
TonB dependent/Ligand-Gated channels are created by a monomeric 22 strand (22,24) ...
83-639
4.85e-19
TonB dependent/Ligand-Gated channels are created by a monomeric 22 strand (22,24) anti-parallel beta-barrel. Ligands apparently bind to the large extracellular loops. The N-terminal 150-200 residues form a plug from the periplasmic end of barrel. Energy (proton-motive force) and TonB-dependent conformational alteration of channel (parts of plug, and loops 7 and 8) allow passage of ligand. FepA residues 12-18 form the TonB box, which mediates the interaction with the TonB-containing inner membrane complex. TonB preferentially interacts with ligand-bound receptors. Transport thru the channel may resemble passage thru an air lock. In this model, ligand binding leads to closure of the extracellular end of pore, then a TonB-mediated signal facillitates opening of the interior side of pore, deforming the N-terminal plug and allowing passage of the ligand to the periplasm. Such a mechanism would prevent the free diffusion of small molecules thru the pore.
Pssm-ID: 238657 [Multi-domain] Cd Length: 635 Bit Score: 91.36 E-value: 4.85e-19
TonB-dependent heme/hemoglobin receptor family protein; This model represents the ...
407-635
8.84e-07
TonB-dependent heme/hemoglobin receptor family protein; This model represents the TonB-dependent outer membrane heme/hemoglobin receptor/transporter found in bacteria which live in contact with animals (which contain hemoglobin or other heme-bearing globins) or legumes (which contain leghemoglobin). Some species having hits to this model such as Nostoc, Caulobacter and Chlorobium do not have an obvious source of hemoglobin-like proteins in their biological niche and so the possibility exists that they act on some other substance. [Transport and binding proteins, Cations and iron carrying compounds, Transport and binding proteins, Porins]
Pssm-ID: 273807 [Multi-domain] Cd Length: 665 Bit Score: 52.01 E-value: 8.84e-07
TonB dependent/Ligand-Gated channels are created by a monomeric 22 strand (22,24) ...
83-639
4.85e-19
TonB dependent/Ligand-Gated channels are created by a monomeric 22 strand (22,24) anti-parallel beta-barrel. Ligands apparently bind to the large extracellular loops. The N-terminal 150-200 residues form a plug from the periplasmic end of barrel. Energy (proton-motive force) and TonB-dependent conformational alteration of channel (parts of plug, and loops 7 and 8) allow passage of ligand. FepA residues 12-18 form the TonB box, which mediates the interaction with the TonB-containing inner membrane complex. TonB preferentially interacts with ligand-bound receptors. Transport thru the channel may resemble passage thru an air lock. In this model, ligand binding leads to closure of the extracellular end of pore, then a TonB-mediated signal facillitates opening of the interior side of pore, deforming the N-terminal plug and allowing passage of the ligand to the periplasm. Such a mechanism would prevent the free diffusion of small molecules thru the pore.
Pssm-ID: 238657 [Multi-domain] Cd Length: 635 Bit Score: 91.36 E-value: 4.85e-19
TonB-dependent heme/hemoglobin receptor family protein; This model represents the ...
407-635
8.84e-07
TonB-dependent heme/hemoglobin receptor family protein; This model represents the TonB-dependent outer membrane heme/hemoglobin receptor/transporter found in bacteria which live in contact with animals (which contain hemoglobin or other heme-bearing globins) or legumes (which contain leghemoglobin). Some species having hits to this model such as Nostoc, Caulobacter and Chlorobium do not have an obvious source of hemoglobin-like proteins in their biological niche and so the possibility exists that they act on some other substance. [Transport and binding proteins, Cations and iron carrying compounds, Transport and binding proteins, Porins]
Pssm-ID: 273807 [Multi-domain] Cd Length: 665 Bit Score: 52.01 E-value: 8.84e-07
TonB-dependent siderophore receptor; This subfamily model encompasses a wide variety of ...
147-639
2.73e-06
TonB-dependent siderophore receptor; This subfamily model encompasses a wide variety of TonB-dependent outer membrane siderophore receptors. It has no overlap with TonB receptors known to transport other substances, but is likely incomplete due to lack of characterizations. It is likely that genuine siderophore receptors will be identified which score below the noise cutoff to this model at which point the model should be updated. [Transport and binding proteins, Cations and iron carrying compounds, Transport and binding proteins, Porins]
Pssm-ID: 273805 [Multi-domain] Cd Length: 651 Bit Score: 50.49 E-value: 2.73e-06
Database: CDSEARCH/cdd Low complexity filter: no Composition Based Adjustment: yes E-value threshold: 0.01
References:
Wang J et al. (2023), "The conserved domain database in 2023", Nucleic Acids Res.51(D)384-8.
Lu S et al. (2020), "The conserved domain database in 2020", Nucleic Acids Res.48(D)265-8.
Marchler-Bauer A et al. (2017), "CDD/SPARCLE: functional classification of proteins via subfamily domain architectures.", Nucleic Acids Res.45(D)200-3.
of the residues that compose this conserved feature have been mapped to the query sequence.
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