BtpA protein explained

Symbol:	BtpA
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.^[2] Homologs of BtpA are found in the Thermoproteota 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. 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.

Notes and References

1. Zak E, Pakrasi HB . 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 . May 2000 . 10806238 . 58995 . 10.1104/pp.123.1.215.
2. Zak E, Norling B, Andersson B, Pakrasi HB . Subcellular localization of the BtpA protein in the cyanobacterium Synechocystis sp. PCC 6803 . Eur. J. Biochem. . 261 . 1 . 311–6 . April 1999 . 10103064 . 10.1046/j.1432-1327.1999.00281.x . free .
3. Boudreau E, Takahashi Y, Lemieux C, Turmel M, Rochaix JD . 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 . October 1997 . 9321389 . 1326293 . 10.1093/emboj/16.20.6095 .
4. Naver H, Boudreau E, Rochaix JD . Functional studies of Ycf3: its role in assembly of photosystem I and interactions with some of its subunits . Plant Cell . 13 . 12 . 2731–45 . December 2001 . 11752384 . 139485 . 10.2307/3871531. 3871531 .