CY561_XENLA
ID CY561_XENLA Reviewed; 247 AA.
AC Q91577;
DT 30-MAY-2000, integrated into UniProtKB/Swiss-Prot.
DT 01-NOV-1996, sequence version 1.
DT 03-AUG-2022, entry version 94.
DE RecName: Full=Transmembrane ascorbate-dependent reductase CYB561 {ECO:0000305};
DE EC=7.2.1.- {ECO:0000250|UniProtKB:P10897};
DE AltName: Full=Cytochrome b-561;
DE AltName: Full=Cytochrome b561;
GN Name=cyb561; Synonyms=xcyt;
OS Xenopus laevis (African clawed frog).
OC Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Amphibia;
OC Batrachia; Anura; Pipoidea; Pipidae; Xenopodinae; Xenopus; Xenopus.
OX NCBI_TaxID=8355;
RN [1]
RP NUCLEOTIDE SEQUENCE [MRNA].
RC TISSUE=Brain;
RX PubMed=8985121; DOI=10.1089/dna.1996.15.1075;
RA Srivastava M.;
RT "Xenopus cytochrome b561: molecular confirmation of a general five
RT transmembrane structure and developmental regulation at the gastrula
RT stage.";
RL DNA Cell Biol. 15:1075-1080(1996).
CC -!- FUNCTION: Transmembrane reductase that uses ascorbate as an electron
CC donor in the cytoplasm and transfers electrons across membranes to
CC reduce monodehydro-L-ascorbate radical in the lumen of secretory
CC vesicles. It is therefore involved the regeneration and homeostasis
CC within secretory vesicles of ascorbate which in turn provides reducing
CC equivalents needed to support the activity of intravesicular enzymes.
CC {ECO:0000250|UniProtKB:P10897}.
CC -!- CATALYTIC ACTIVITY:
CC Reaction=L-ascorbate(in) + monodehydro-L-ascorbate radical(out) = L-
CC ascorbate(out) + monodehydro-L-ascorbate radical(in);
CC Xref=Rhea:RHEA:66524, ChEBI:CHEBI:38290, ChEBI:CHEBI:59513;
CC Evidence={ECO:0000250|UniProtKB:P10897};
CC PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:66525;
CC Evidence={ECO:0000250|UniProtKB:P10897};
CC -!- COFACTOR:
CC Name=heme b; Xref=ChEBI:CHEBI:60344;
CC Evidence={ECO:0000250|UniProtKB:P10897};
CC Note=Binds 2 heme b groups non-covalently.
CC {ECO:0000250|UniProtKB:P10897};
CC -!- SUBCELLULAR LOCATION: Cytoplasmic vesicle, secretory vesicle,
CC chromaffin granule membrane {ECO:0000250|UniProtKB:P10897}; Multi-pass
CC membrane protein {ECO:0000250|UniProtKB:Q53TN4}. Note=Secretory vesicle
CC containing catecholamines and amidated peptides.
CC {ECO:0000250|UniProtKB:P10897}.
CC -!- TISSUE SPECIFICITY: Specific to neuroendocrine tissues.
CC -!- DEVELOPMENTAL STAGE: Developmentally regulated at the gastrula stage.
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DR EMBL; U16364; AAA65644.1; -; mRNA.
DR AlphaFoldDB; Q91577; -.
DR SMR; Q91577; -.
DR Proteomes; UP000186698; Genome assembly.
DR GO; GO:0042584; C:chromaffin granule membrane; ISS:UniProtKB.
DR GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-KW.
DR GO; GO:0046872; F:metal ion binding; IEA:UniProtKB-KW.
DR GO; GO:0140575; F:transmembrane monodehydroascorbate reductase activity; ISS:UniProtKB.
DR GO; GO:0140576; P:ascorbate homeostasis; ISS:UniProtKB.
DR InterPro; IPR028837; CYB561.
DR InterPro; IPR043205; CYB561/CYBRD1-like.
DR InterPro; IPR006593; Cyt_b561/ferric_Rdtase_TM.
DR PANTHER; PTHR10106; PTHR10106; 1.
DR PANTHER; PTHR10106:SF14; PTHR10106:SF14; 1.
DR Pfam; PF03188; Cytochrom_B561; 1.
DR SMART; SM00665; B561; 1.
DR PROSITE; PS50939; CYTOCHROME_B561; 1.
PE 2: Evidence at transcript level;
KW Cytoplasmic vesicle; Electron transport; Heme; Iron; Membrane;
KW Metal-binding; Reference proteome; Translocase; Transmembrane;
KW Transmembrane helix; Transport.
FT CHAIN 1..247
FT /note="Transmembrane ascorbate-dependent reductase CYB561"
FT /id="PRO_0000151032"
FT TOPO_DOM 1..9
FT /note="Cytoplasmic"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT TRANSMEM 10..30
FT /note="Helical"
FT /evidence="ECO:0000255"
FT TOPO_DOM 31..51
FT /note="Vesicular"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT TRANSMEM 52..72
FT /note="Helical"
FT /evidence="ECO:0000255"
FT TOPO_DOM 73..84
FT /note="Cytoplasmic"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT TRANSMEM 85..105
FT /note="Helical"
FT /evidence="ECO:0000255"
FT TOPO_DOM 106..124
FT /note="Vesicular"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT TRANSMEM 125..145
FT /note="Helical"
FT /evidence="ECO:0000255"
FT TOPO_DOM 146..158
FT /note="Cytoplasmic"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT TRANSMEM 159..179
FT /note="Helical"
FT /evidence="ECO:0000255"
FT TOPO_DOM 180..194
FT /note="Vesicular"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT TRANSMEM 195..215
FT /note="Helical"
FT /evidence="ECO:0000255"
FT TOPO_DOM 216..247
FT /note="Cytoplasmic"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT DOMAIN 19..216
FT /note="Cytochrome b561"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00242"
FT BINDING 53
FT /ligand="heme b"
FT /ligand_id="ChEBI:CHEBI:60344"
FT /ligand_label="1"
FT /ligand_part="Fe"
FT /ligand_part_id="ChEBI:CHEBI:18248"
FT /note="axial binding residue"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT BINDING 73
FT /ligand="heme b"
FT /ligand_id="ChEBI:CHEBI:60344"
FT /ligand_label="2"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT BINDING 80
FT /ligand="heme b"
FT /ligand_id="ChEBI:CHEBI:60344"
FT /ligand_label="2"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT BINDING 80
FT /ligand="L-ascorbate"
FT /ligand_id="ChEBI:CHEBI:38290"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT BINDING 84
FT /ligand="L-ascorbate"
FT /ligand_id="ChEBI:CHEBI:38290"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT BINDING 87
FT /ligand="heme b"
FT /ligand_id="ChEBI:CHEBI:60344"
FT /ligand_label="2"
FT /ligand_part="Fe"
FT /ligand_part_id="ChEBI:CHEBI:18248"
FT /note="axial binding residue"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT BINDING 116..119
FT /ligand="heme b"
FT /ligand_id="ChEBI:CHEBI:60344"
FT /ligand_label="1"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT BINDING 121
FT /ligand="heme b"
FT /ligand_id="ChEBI:CHEBI:60344"
FT /ligand_label="1"
FT /ligand_part="Fe"
FT /ligand_part_id="ChEBI:CHEBI:18248"
FT /note="axial binding residue"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT BINDING 153
FT /ligand="L-ascorbate"
FT /ligand_id="ChEBI:CHEBI:38290"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT BINDING 160
FT /ligand="heme b"
FT /ligand_id="ChEBI:CHEBI:60344"
FT /ligand_label="2"
FT /ligand_part="Fe"
FT /ligand_part_id="ChEBI:CHEBI:18248"
FT /note="axial binding residue"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT BINDING 181
FT /ligand="heme b"
FT /ligand_id="ChEBI:CHEBI:60344"
FT /ligand_label="1"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
FT BINDING 221
FT /ligand="heme b"
FT /ligand_id="ChEBI:CHEBI:60344"
FT /ligand_label="2"
FT /evidence="ECO:0000250|UniProtKB:Q53TN4"
SQ SEQUENCE 247 AA; 27712 MW; 959D6DA963350C8C CRC64;
MENALSSQNL GFMPYLVAGS QILGIANLAI TGAWLAQLQR RFLWSGPLQF NVHPLCMVLG
MVFLCGEALL VYRVFRHETK RSTKILHGVL HIMALVISLV GVIAVFQYHQ ANGYPDMYSL
HSWCGIVTFT LYILQWIIGF SLFFIPGVAF TYRSQFKPLH EFFGRALFLS SIATSLLGLT
EKMFSEYSSH PAEGILVNSL GVLLVVFGAV IAYILTREDW RRPPLPEEQA LSMDFKTLTE
GDSPTDQ
