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0  structures 925  species 0  interactions 1187  sequences 8  architectures

Family: BtpA (PF03437)

Summary: BtpA family

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This is the Wikipedia entry entitled "BtpA protein". More...

BtpA protein Edit Wikipedia article

Symbol BtpA
Pfam PF03437
Pfam clan CL0036
InterPro IPR005137

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 .[1] It is an extrinsic membrane protein located on the cytoplasmic side of the thylakoid membrane.[1][2] 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.[3] Ycf4 co-fractionates with a protein complex larger than PSI upon sucrose density gradient centrifugation of solubilised thylakoids.[3] 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.[4] 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.


  1. ^ a b 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): 215–22. doi:10.1104/pp.123.1.215. PMC 58995Freely accessible. PMID 10806238. 
  2. ^ 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): 311–6. doi:10.1046/j.1432-1327.1999.00281.x. PMID 10103064. 
  3. ^ a b 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): 6095–104. doi:10.1093/emboj/16.20.6095. PMC 1326293Freely accessible. PMID 9321389. 
  4. ^ 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): 2731–45. doi:10.2307/3871531. PMC 139485Freely accessible. PMID 11752384. 

This article incorporates text from the public domain Pfam and InterPro IPR005137

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

BtpA family Provide feedback

The BtpA protein is tightly associated with the thylakoid membranes, where it stabilises the reaction centre proteins of photosystem I.

Literature references

  1. 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

Internal database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR005137

Members of this family are found in Caenorhabditis elegans, Synechocystis sp., E. coli, and several of the Archaea. Members in Cyanobacteria have been shown to play a role in protein complex biogenesis, and designated BtpA (biogenesis of thylakoid protein) [ PUBMED:9045660 , PUBMED:12651001 ]. BtpA appears to act at the level of Photosystem I (PSI) stabilisation [ PUBMED:10806238 ]. Homologues in non-photosynthetic species, where thylakoid intracytoplasmic membranes are lacking, are likely to act elsewhere in membrane protein biogenesis.

Domain organisation

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Curation and family details

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Seed source: Pfam-B_4453 (release 6.6)
Previous IDs: none
Type: Family
Sequence Ontology: SO:0100021
Author: Finn RD
Number in seed: 5
Number in full: 1187
Average length of the domain: 240.80 aa
Average identity of full alignment: 33 %
Average coverage of the sequence by the domain: 90.88 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 57096847 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 20.2 20.2
Trusted cut-off 20.2 20.2
Noise cut-off 20.1 20.1
Model length: 254
Family (HMM) version: 17
Download: download the raw HMM for this family

Species distribution

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Archea Archea Eukaryota Eukaryota
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AlphaFold Structure Predictions

The list of proteins below match this family and have AlphaFold predicted structures. Click on the protein accession to view the predicted structure.

Protein Predicted structure External Information
A0A0R4ISR8 View 3D Structure Click here
P39364 View 3D Structure Click here
Q1NZ26 View 3D Structure Click here
Q58515 View 3D Structure Click here
Q9VS44 View 3D Structure Click here

trRosetta Structure

The structural model below was generated by the Baker group with the trRosetta software using the Pfam UniProt multiple sequence alignment.

The InterPro website shows the contact map for the Pfam SEED alignment. Hovering or clicking on a contact position will highlight its connection to other residues in the alignment, as well as on the 3D structure.

Improved protein structure prediction using predicted inter-residue orientations. Jianyi Yang, Ivan Anishchenko, Hahnbeom Park, Zhenling Peng, Sergey Ovchinnikov, David Baker Proceedings of the National Academy of Sciences Jan 2020, 117 (3) 1496-1503; DOI: 10.1073/pnas.1914677117;