| Apocytochr_F_C | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| cytochrome f from the b6f complex of phormidium laminosum | |||||||||
| Identifiers | |||||||||
| Symbol | Apocytochr_F_C | ||||||||
| Pfam | PF01333 | ||||||||
| Pfam clan | CL0105 | ||||||||
| InterPro | IPR002325 | ||||||||
| PROSITE | PDOC00169 | ||||||||
| SCOP | 1ctm | ||||||||
| TCDB | 3.D.3 | ||||||||
|
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Cytochrome f is the largest subunit of cytochrome b6f complex (plastoquinol—plastocyanin reductase; EC 1.10.99.1). In its structure and functions, the cytochrome b6f complex bears extensive analogy to the cytochrome bc1 complex of mitochondria and photosynthetic purple bacteria. Cytochrome f (cyt f) plays a role analogous to that of cytochrome c1, in spite of their different structures.[1]
The 3D structure of Brassica rapa (Turnip) cyt f has been determined.[2] The lumen-side segment of cyt f includes two structural domains: a small one above a larger one that, in turn, is on top of the attachment to the membrane domain. The large domain consists of an anti-parallel beta-sandwich and a short haem-binding peptide, which form a three-layer structure. The small domain is inserted between beta-strands F and G of the large domain and is an all-beta domain. The haem nestles between two short helices at the N terminus of cyt f. Within the second helix is the sequence motif for the c-type cytochromes, CxxCH (residues 21-25), which is covalently attached to the haem through thioether bonds to Cys-21 and Cys-24. His-25 is the fifth haem iron ligand. The sixth haem iron ligand is the alpha-amino group of Tyr-1 in the first helix.[2] Cyt f has an internal network of water molecules that may function as a proton wire.[2] The water chain appears to be a conserved feature of cyt f.
This article incorporates text from the public domain Pfam and InterPro IPR002325