ID 7.1.1.6 DE plastoquinol--plastocyanin reductase. AN cytochrome b6f complex. CA a plastoquinol + 2 H(+)(in) + 2 oxidized [plastocyanin] = a plastoquinone CA + 4 H(+)(out) + 2 reduced [plastocyanin]. CC -!- Contains two b-type cytochromes, two c-type cytochromes (cn and f), CC and a [2Fe-2S] Rieske cluster. CC -!- The enzyme plays a key role in photosynthesis, transferring electrons CC from photosystem II (EC 1.10.3.9) to photosystem I (EC 1.97.1.12). CC -!- Cytochrome c-552 can act as acceptor instead of plastocyanin, CC but more slowly. CC -!- In chloroplasts, protons are translocated through the thylakoid CC membrane from the lumen to the stroma. CC -!- The mechanism occurs through the Q cycle as in EC 7.1.1.8 (complex CC III) and involves electron bifurcation. CC -!- Formerly EC 1.10.9.1 and EC 1.10.99.1. DR Q9ZR03, UCRIA_ARATH; Q7XYM4, UCRIA_BIGNA; P49728, UCRIA_CHLRE; DR Q5CC93, UCRIA_CYAPA; O49078, UCRIA_FRIAG; Q93SX0, UCRIA_NOSS1; DR Q69S39, UCRIA_ORYSJ; P26291, UCRIA_PEA ; Q69GY7, UCRIA_SOLTU; DR P08980, UCRIA_SPIOL; P74714, UCRIA_SYNY3; P30361, UCRIA_TOBAC; DR Q9L3P9, UCRIA_TRIV2; Q9SBN3, UCRIA_VOLCA; Q7X9A6, UCRIA_WHEAT; DR Q5CC92, UCRIB_CYAPA; Q93SW8, UCRIB_NOSS1; P26290, UCRIB_SYNY3; DR Q02585, UCRIB_TOBAC; Q93SW6, UCRIB_TRIV2; P70758, UCRIC_NOSS1; DR Q9F722, UCRI_CHLTE ; Q46136, UCRI_CHLTI ; B8HNR1, UCRI_CYAP4 ; DR P14698, UCRI_DESSP ; Q7NCE1, UCRI_GLOVI ; P83794, UCRI_MASLA ; DR B0JXB7, UCRI_MICAN ; B2J3K2, UCRI_NOSP7 ; Q7U566, UCRI_PARMW ; DR P26292, UCRI_PICP2 ; A3PBI5, UCRI_PROM0 ; A2C0R9, UCRI_PROM1 ; DR A8G3H7, UCRI_PROM2 ; A2C7F6, UCRI_PROM3 ; A9BE84, UCRI_PROM4 ; DR A2BVC4, UCRI_PROM5 ; Q31C72, UCRI_PROM9 ; Q7VDC0, UCRI_PROMA ; DR Q7V654, UCRI_PROMM ; Q7V2L4, UCRI_PROMP ; A2BPU5, UCRI_PROMS ; DR Q46GW1, UCRI_PROMT ; Q31NV7, UCRI_SYNE7 ; P0C8N7, UCRI_SYNEL ; DR Q2JUP1, UCRI_SYNJA ; Q2JL39, UCRI_SYNJB ; Q5N5B0, UCRI_SYNP6 ; DR A5GMW1, UCRI_SYNPW ; A5GRU8, UCRI_SYNR3 ; Q0I872, UCRI_SYNS3 ; DR Q3AWL7, UCRI_SYNS9 ; Q3ALY0, UCRI_SYNSC ; P0C8N8, UCRI_THEVB ; DR Q114L6, UCRI_TRIEI ; //