ID   CYB5_BOROF              Reviewed;         132 AA.
AC   O04354;
DT   11-JAN-2001, integrated into UniProtKB/Swiss-Prot.
DT   01-JUL-1997, sequence version 1.
DT   03-AUG-2022, entry version 91.
DE   RecName: Full=Cytochrome b5;
OS   Borago officinalis (Bourrache) (Borage).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   asterids; lamiids; Boraginales; Boraginaceae; Boraginoideae; Boragineae;
OC   Boragininae; Borago.
OX   NCBI_TaxID=13363;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RX   PubMed=9108131; DOI=10.1073/pnas.94.8.4211;
RA   Sayanova O., Smith M.A., Lapinskas P.A., Stobart K., Dobson G.,
RA   Christie W.W., Shewry P.R., Napier J.A.;
RT   "Expression of a borage desaturase cDNA containing an N-terminal cytochrome
RT   b5 domain results in the accumulation of high levels of delta6-desaturated
RT   fatty acids in transgenic tobacco.";
RL   Proc. Natl. Acad. Sci. U.S.A. 94:4211-4216(1997).
CC   -!- FUNCTION: Membrane bound hemoprotein which function as an electron
CC       carrier for several membrane bound oxygenases. {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Endoplasmic reticulum membrane {ECO:0000250};
CC       Single-pass membrane protein {ECO:0000250}; Cytoplasmic side
CC       {ECO:0000250}. Microsome membrane {ECO:0000250}; Single-pass membrane
CC       protein {ECO:0000250}; Cytoplasmic side {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the cytochrome b5 family. {ECO:0000305}.
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DR   EMBL; U79011; AAC49701.1; -; mRNA.
DR   AlphaFoldDB; O04354; -.
DR   SMR; O04354; -.
DR   GO; GO:0005789; C:endoplasmic reticulum membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-KW.
DR   GO; GO:0020037; F:heme binding; IEA:InterPro.
DR   GO; GO:0046872; F:metal ion binding; IEA:UniProtKB-KW.
DR   Gene3D; 3.10.120.10; -; 1.
DR   InterPro; IPR001199; Cyt_B5-like_heme/steroid-bd.
DR   InterPro; IPR036400; Cyt_B5-like_heme/steroid_sf.
DR   InterPro; IPR018506; Cyt_B5_heme-BS.
DR   Pfam; PF00173; Cyt-b5; 1.
DR   PRINTS; PR00363; CYTOCHROMEB5.
DR   SMART; SM01117; Cyt-b5; 1.
DR   SUPFAM; SSF55856; SSF55856; 1.
DR   PROSITE; PS00191; CYTOCHROME_B5_1; 1.
DR   PROSITE; PS50255; CYTOCHROME_B5_2; 1.
PE   2: Evidence at transcript level;
KW   Electron transport; Endoplasmic reticulum; Heme; Iron; Membrane;
KW   Metal-binding; Microsome; Transmembrane; Transmembrane helix; Transport.
FT   CHAIN           1..132
FT                   /note="Cytochrome b5"
FT                   /id="PRO_0000166022"
FT   TRANSMEM        104..124
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   DOMAIN          2..78
FT                   /note="Cytochrome b5 heme-binding"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00279"
FT   BINDING         37
FT                   /ligand="heme"
FT                   /ligand_id="ChEBI:CHEBI:30413"
FT                   /ligand_part="Fe"
FT                   /ligand_part_id="ChEBI:CHEBI:18248"
FT                   /note="axial binding residue"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00279"
FT   BINDING         61
FT                   /ligand="heme"
FT                   /ligand_id="ChEBI:CHEBI:30413"
FT                   /ligand_part="Fe"
FT                   /ligand_part_id="ChEBI:CHEBI:18248"
FT                   /note="axial binding residue"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00279"
SQ   SEQUENCE   132 AA;  14557 MW;  96EF72A06F2E8C5B CRC64;
     MGKIFTLAEV AQHNNSKDCW LIINGKVYDV TKFLEDHPGG DDVLLSATGK DATDDFEDIG
     HSSSAKAMLD EYYVGDIDSS SIPSQVKYTP PKQPLYNPDK TREFVIKLLQ FLVPLVILAG
     AIGIRFYTKS SA