- Orange carotenoid N-terminal domain
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Carot_N crystal structure of orange carotenoid protein Identifiers Symbol Carot_N Pfam PF09150 InterPro IPR015233 SCOP 1m98 Available protein structures: Pfam structures PDB RCSB PDB; PDBe PDBsum structure summary In molecular biology the orange carotenoid N-terminal domain is a protein domain found predominantly at the N-terminus of prokaryotic orange carotenoid proteins and in related carotenoid-binding proteins. It adopts an alpha-helical structure consisting of two four-helix bundles.[1]
Orange carotenoid-binding proteins (OCP) were first identified in cyanobacterial species, where they occur associated with phycobilisome in the cellular thylakoid membrane. These proteins function in photoprotection, and are essential for inhibiting white and blue-green light non-photochemical quenching (NPQ).[2][3] Carotenoids improve the photoprotectant activity by broadening OCP's absorption spectrum and facilitating the dissipation of absorbed energy. OCP acts as a homodimer, and binds one molecule of carotenoid (3'-hydroxyechinenone) and one chloride ion per subunit, where the carotenoid binding site is lined with a striking number of methionine residues. The carotenoid 3'-hydroxyechinenone is not found in higher plants. OCP has two domains: an N-terminal helical domain and a C-terminal domain that resembles a NTF2 (nuclear transport factor 2) domain. OCP can be proteolytically cleaved into a red form (RCP), which lacks 15 residues from the N terminus and approximately 150 residues from the C terminus.[4]
References
- ^ Kerfeld CA, Sawaya MR, Brahmandam V, Cascio D, Ho KK, Trevithick-Sutton CC, Krogmann DW, Yeates TO (January 2003). "The crystal structure of a cyanobacterial water-soluble carotenoid binding protein". Structure 11 (1): 55–65. doi:10.1016/S0969-2126(02)00936-X. PMID 12517340.
- ^ Wilson A, Boulay C, Wilde A, Kerfeld CA, Kirilovsky D (February 2007). "Light-induced energy dissipation in iron-starved cyanobacteria: roles of OCP and IsiA proteins". Plant Cell 19 (2): 656–72. doi:10.1105/tpc.106.045351. PMC 1867334. PMID 17307930. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1867334.
- ^ Wilson A, Ajlani G, Verbavatz JM, Vass I, Kerfeld CA, Kirilovsky D (April 2006). "A soluble carotenoid protein involved in phycobilisome-related energy dissipation in cyanobacteria". Plant Cell 18 (4): 992–1007. doi:10.1105/tpc.105.040121. PMC 1425857. PMID 16531492. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1425857.
- ^ Kerfeld CA (2004). "Structure and function of the water-soluble carotenoid-binding proteins of cyanobacteria". Photosyn. Res. 81 (3): 215–25. doi:10.1023/B:PRES.0000036886.60187.c8. PMID 16034528.
This article includes text from the public domain Pfam and InterPro IPR015233
Categories:- Protein domains
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