Summary: TrkA-N domain
TrkA-N domain Provide feedback
Schlosser A, Hamann A, Bossemeyer D, Schneider E, Bakker EP; , Mol Microbiol 1993;9:533-543.: NAD+ binding to the Escherichia coli K(+)-uptake protein TrkA and sequence similarity between TrkA and domains of a family of dehydrogenases suggest a role for NAD+ in bacterial transport. PUBMED:8412700 EPMC:8412700
Anantharaman V, Koonin EV, Aravind L; , J Mol Biol 2001;307:1271-1292.: Regulatory potential, phyletic distribution and evolution of ancient, intracellular small-molecule-binding domains. PUBMED:11292341 EPMC:11292341
Internal database links
|Similarity to PfamA using HHSearch:||3Beta_HSD Pyr_redox Saccharop_dh AlaDh_PNT_C 2-Hacid_dh_C 3HCDH_N AdoHcyase_NAD ApbA F420_oxidored NAD_binding_2 NAD_Gly3P_dh_N Shikimate_DH UDPG_MGDP_dh_N NmrA NAD_binding_7 NAD_binding_10 Methyltransf_31|
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR003148
The regulator of K+ conductance (RCK) domain is found in many ligand-gated K+ channels, most often attached to the intracellular carboxy terminus. The domain is prevalent among prokaryotic K+ channels, and also found in eukaryotic, high-conductance Ca2+-activated K+ channels (BK channels) [PUBMED:11292341, PUBMED:11301020, PUBMED:12037559]. Largely involved in redox-linked regulation of potassium channels, the N-terminal part of the RCK domain is predicted to be an active dehydrogenase at least in some cases [PUBMED:11292341]. Some have a conserved sequence motif (G-x-G-x-x-G-x(n)-[DE]) for NAD+ binding [PUBMED:8412700], but others do not, reflecting the diversity of ligands for RCK domains. The C-terminal part is less conserved, being absent in some channels, such as the kefC antiporter from Escherichia coli. It is predicted to bind unidentified ligands and to regulate sulphate, sodium and other transporters.
The X-ray structure of several RCK domains has been solved [PUBMED:16227203, PUBMED:11301020, PUBMED:12037559]. It reveals an alpha-beta fold similar to dehydrogenase enzymes. The domain forms a homodimer, producing a cleft between two lobes. It has a composite structure, with an N-terminal (RCK-N), and a C-terminal (RCK-C) subdomain. The RCK-N subdomain forms a Rossmann fold with two alpha helices on one side of a six stranded parallel beta sheet and three alpha helices on the other side. The RCK-C subdomain is an all-beta-strand fold. It forms an extention of the dimer interface and further stabilises the RCK homodimer [PUBMED:16227203, PUBMED:11301020, PUBMED:12037559]. Ca2+ is a ligand that opens the channel in a concentration-dependent manner. Two Ca2+ ions are located at the base of a cleft between two RCK domains, coordinated by the carboxylate groups of two glutamate residues, and by an aspartate residue [PUBMED:16227203, PUBMED:11301020, PUBMED:12037559].
RCK domains occur in at least five different contexts:
- As a single domain on the C terminus of some K+ channels (for example, many prokaryotic K+ channels).
- As two tandem RCK domains on the C terminus of some transporters that form gating rings (for example, eukaryotic BK channels). The gating ring has an arrangement of eight identical RCK domains, one from each of the four pore-forming subunits and four from the intracellular solution.
- As two domains, one at the N terminus and another at the C terminus of transporter (for example, the prokaryotic trk system potassium uptake protein A).
- As a soluble protein (not part of a K+ channel) consisting of two tandem RCK domains.
- As a soluble protein consisting of a single RCK domain.
This entry represents the N-terminal subdomain of RCK.
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Biological process||potassium ion transport (GO:0006813)|
- the number of sequences which exhibit this architecture
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This example describes an architecture with one
Gladomain, followed by two consecutive
EGFdomains, and finally a single
- the UniProt description of the protein sequence
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A class of redox enzymes are two domain proteins. One domain, termed the catalytic domain, confers substrate specificity and the precise reaction of the enzyme. The other domain, which is common to this class of redox enzymes, is a Rossmann-fold domain. The Rossmann domain binds nicotinamide adenine dinucleotide (NAD+) and it is this cofactor that reversibly accepts a hydride ion, which is lost or gained by the substrate in the redox reaction. Rossmann domains have an alpha/beta fold, which has a central beta sheet, with approximately five alpha helices found surrounding the beta sheet.The strands forming the beta sheet are found in the following characteristic order 654123. The inter sheet crossover of the stands in the sheet form the NAD+ binding site . In some more distantly relate Rossmann domains the NAD+ cofactor is replaced by the functionally similar cofactor FAD.
The clan contains the following 180 members:2-Hacid_dh_C 3Beta_HSD 3HCDH_N adh_short adh_short_C2 ADH_zinc_N ADH_zinc_N_2 AdoHcyase_NAD AdoMet_MTase AlaDh_PNT_C Amino_oxidase ApbA AviRa Bac_GDH Bin3 CheR CMAS CmcI CoA_binding CoA_binding_2 CoA_binding_3 Cons_hypoth95 DAO DapB_N DFP DNA_circ_N DNA_methylase DOT1 DREV dTMP_synthase DUF1442 DUF1776 DUF2431 DUF268 DUF3321 DUF43 DUF633 DUF938 DXP_redisom_C DXP_reductoisom Eco57I ELFV_dehydrog Eno-Rase_FAD_bd Eno-Rase_NADH_b Enoyl_reductase Epimerase F420_oxidored FAD_binding_2 FAD_binding_3 FAD_oxidored Fibrillarin FMO-like FmrO FtsJ G-7-MTase G6PD_N GCD14 GDI GFO_IDH_MocA GIDA GidB GLF Glyco_hydro_4 GMC_oxred_N Gp_dh_N GRAS GRDA HI0933_like HIM1 IlvN K_oxygenase KR LCM Ldh_1_N Lycopene_cycl Malic_M Mannitol_dh Met_10 Methyltrans_Mon Methyltrans_SAM Methyltransf_10 Methyltransf_11 Methyltransf_12 Methyltransf_15 Methyltransf_16 Methyltransf_17 Methyltransf_18 Methyltransf_19 Methyltransf_2 Methyltransf_20 Methyltransf_21 Methyltransf_22 Methyltransf_23 Methyltransf_24 Methyltransf_25 Methyltransf_26 Methyltransf_27 Methyltransf_28 Methyltransf_29 Methyltransf_3 Methyltransf_30 Methyltransf_31 Methyltransf_32 Methyltransf_4 Methyltransf_5 Methyltransf_7 Methyltransf_8 Methyltransf_9 Methyltransf_PK MethyltransfD12 MetW Mg-por_mtran_C Mqo MT-A70 MTS Mur_ligase N2227 N6-adenineMlase N6_Mtase N6_N4_Mtase NAD_binding_10 NAD_binding_11 NAD_binding_2 NAD_binding_3 NAD_binding_4 NAD_binding_5 NAD_binding_7 NAD_binding_8 NAD_binding_9 NAD_Gly3P_dh_N NAS NmrA NNMT_PNMT_TEMT NodS Nol1_Nop2_Fmu Nol1_Nop2_Fmu_2 NSP13 OCD_Mu_crystall PARP_regulatory PCMT PDH Polysacc_synt_2 Pox_MCEL Prenylcys_lyase PrmA PRMT5 Pyr_redox Pyr_redox_2 Pyr_redox_3 RmlD_sub_bind Rossmann-like rRNA_methylase RrnaAD Rsm22 RsmJ Saccharop_dh SAM_MT SE Semialdhyde_dh Shikimate_DH Spermine_synth Strep_67kDa_ant TehB THF_DHG_CYH_C Thi4 ThiF TPMT TrkA_N TRM TRM13 tRNA_U5-meth_tr Trp_halogenase TylF Ubie_methyltran UDPG_MGDP_dh_N UPF0020 UPF0146 V_cholerae_RfbT XdhC_C YjeF_N
We make a range of alignments for each Pfam-A family:
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Curation and family details
|Seed source:||Pfam-B_289 (Release 5.3)|
|Number in seed:||219|
|Number in full:||14934|
|Average length of the domain:||116.30 aa|
|Average identity of full alignment:||21 %|
|Average coverage of the sequence by the domain:||31.04 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||13|
|Download:||download the raw HMM for this family|
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the TrkA_N domain has been found. There are 85 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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