Summary: BtpA family
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BtpA protein Edit Wikipedia article
In molecular biology, the BtpA protein family is a family of proteins which includes BtpA. BtpA appears to play a role in the stabilisation of photosystem I . It is an extrinsic membrane protein located on the cytoplasmic side of the thylakoid membrane. Homologs of BtpA are found in the crenarchaeota and euryarchaeota, where their function remains unknown. The Ycf4 protein is firmly associated with the thylakoid membrane, presumably through a transmembrane domain. Ycf4 co-fractionates with a protein complex larger than PSI upon sucrose density gradient centrifugation of solubilised thylakoids. The Ycf3 protein is loosely associated with the thylakoid membrane and can be released from the membrane with sodium carbonate. This suggests that Ycf3 is not part of a stable complex and that it probably interacts transiently with its partners. Ycf3 contains a number of tetratricopeptide repeats (TPR); TPR is a structural motif present in a wide range of proteins, which mediates protein-protein interactions.
- Zak E, Pakrasi HB (May 2000). "The BtpA protein stabilizes the reaction center proteins of photosystem I in the cyanobacterium Synechocystis sp. PCC 6803 at low temperature". Plant Physiol. 123 (1): 215â22. doi:10.1104/pp.123.1.215. PMC 58995. PMID 10806238.
- Zak E, Norling B, Andersson B, Pakrasi HB (April 1999). "Subcellular localization of the BtpA protein in the cyanobacterium Synechocystis sp. PCC 6803". Eur. J. Biochem. 261 (1): 311â6. doi:10.1046/j.1432-1327.1999.00281.x. PMID 10103064.
- Boudreau E, Takahashi Y, Lemieux C, Turmel M, Rochaix JD (October 1997). "The chloroplast ycf3 and ycf4 open reading frames of Chlamydomonas reinhardtii are required for the accumulation of the photosystem I complex". EMBO J. 16 (20): 6095â104. doi:10.1093/emboj/16.20.6095. PMC 1326293. PMID 9321389.
- Naver H, Boudreau E, Rochaix JD (December 2001). "Functional studies of Ycf3: its role in assembly of photosystem I and interactions with some of its subunits". Plant Cell 13 (12): 2731â45. PMC 139485. PMID 11752384.
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The BtpA protein is tightly associated with the thylakoid membranes, where it stabilises the reaction centre proteins of photosystem I.
Zak E, Pakrasi HB; , Plant Physiol 2000;123:215-222.: The BtpA protein stabilizes the reaction center proteins of photosystem I in the cyanobacterium Synechocystis sp. PCC 6803 at low temperature. PUBMED:10806238 EPMC:10806238
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR005137
Photosystem I (PSI) is a large protein complex embedded within the photosynthetic thylakoid membrane. It consists of 11 subunits, ~100 chlorophyll a molecules, 2 phylloquinones, and 3 Fe4S4-clusters. The three dimensional structure of the PSI complex has been resolved at 2.5 A [PUBMED:11418848], which allows the precise localisation of each cofactor. PSI together with photosystem II (PSII) catalyses the light-induced steps in oxygenic photosynthesis - a process found in cyanobacteria, eukaryotic algae (e.g. red algae, green algae) and higher plants.
To date, three thylakoid proteins involved in the stable accumulation of PSI have been identified: BtpA [PUBMED:9045660], Ycf3 [PUBMED:9321389, PUBMED:9314531], and Ycf4 (INTERPRO) [PUBMED:9321389]. Because translation of the psaA and psaB mRNAs encoding the two reaction centre polypeptides, of PSI and PSII respectively, is not affected in mutant strains lacking functional ycf3 and ycf4, the products of these two genes appear to act at a post-translational step of PSI biosynthesis. These gene products are therefore involved either in the stabilisation or in the assembly of the PSI complex. However, their exact roles remain unknown. The BtpA protein appears to act at the level of PSI stabilisation [PUBMED:10806238]. It is an extrinsic membrane protein located on the cytoplasmic side of the thylakoid membrane [PUBMED:10103064, PUBMED:10806238]. Homologs of BtpA are found in the crenarchaeota and euryarchaeota, where their function remains unknown. The Ycf4 protein is firmly associated with the thylakoid membrane, presumably through a transmembrane domain [PUBMED:9321389]. Ycf4 co-fractionates with a protein complex larger than PSI upon sucrose density gradient centrifugation of solubilised thylakoids [PUBMED:9321389]. The Ycf3 protein is loosely associated with the thylakoid membrane and can be released from the membrane with sodium carbonate. This suggests that Ycf3 is not part of a stable complex and that it probably interacts transiently with its partners [PUBMED:11752384]. Ycf3 contains a number of tetratrico peptide repeats (TPR, INTERPRO); TPR is a structural motif present in a wide range of proteins, which mediates protein-protein interactions.
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This large superfamily of TIM barrel enzymes all contain a common phosphate binding site. The phosphate is found in a variety of cofactors and ligands such as FMN [1,2].
The clan contains the following 57 members:Ala_racemase_N ALAD Aldolase AP_endonuc_2 BtpA CdhD CutC DAHP_synth_1 DAHP_synth_2 DeoC DHDPS DHO_dh DHquinase_I DUF1341 DUF2090 DUF556 DUF561 DUF692 DUF993 Dus F_bP_aldolase FMN_dh G3P_antiterm Glu_syn_central Glu_synthase His_biosynth HMGL-like IGPS IMPDH iPGM_N MtrH NanE NAPRTase NeuB NMO OMPdecase Orn_Arg_deC_N Oxidored_FMN PcrB PdxJ PhosphMutase PRAI Pterin_bind QRPTase_C Racemase_4 RhaA Ribul_P_3_epim SOR_SNZ Tagatose_6_P_K ThiG TIM TIM-br_sig_trns TMP-TENI Transaldolase Trp_syntA UvdE UxuA
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Curation and family details
|Seed source:||Pfam-B_4453 (release 6.6)|
|Number in seed:||6|
|Number in full:||562|
|Average length of the domain:||246.50 aa|
|Average identity of full alignment:||36 %|
|Average coverage of the sequence by the domain:||93.56 %|
|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:||10|
|Download:||download the raw HMM for this family|
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