ID   FAD3E_TOBAC             Reviewed;         379 AA.
AC   P48626;
DT   01-FEB-1996, integrated into UniProtKB/Swiss-Prot.
DT   01-FEB-1996, sequence version 1.
DT   25-MAY-2022, entry version 92.
DE   RecName: Full=Omega-3 fatty acid desaturase, endoplasmic reticulum;
DE            EC=1.14.19.-;
GN   Name=FAD3;
OS   Nicotiana tabacum (Common tobacco).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   asterids; lamiids; Solanales; Solanaceae; Nicotianoideae; Nicotianeae;
OC   Nicotiana.
OX   NCBI_TaxID=4097;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   STRAIN=cv. SR1; TISSUE=Leaf;
RX   PubMed=7926817; DOI=10.1016/0378-1119(94)90084-1;
RA   Hamada T., Kodama H., Nishimura M., Iba K.;
RT   "Cloning of a cDNA encoding tobacco omega-3 fatty acid desaturase.";
RL   Gene 147:293-294(1994).
CC   -!- FUNCTION: ER (microsomal) omega-3 fatty acid desaturase introduces the
CC       third double bond in the biosynthesis of 18:3 fatty acids, important
CC       constituents of plant membranes. It is thought to use cytochrome b5 as
CC       an electron donor and to act on fatty acids esterified to
CC       phosphatidylcholine and, possibly, other phospholipids.
CC   -!- PATHWAY: Lipid metabolism; polyunsaturated fatty acid biosynthesis.
CC   -!- SUBCELLULAR LOCATION: Endoplasmic reticulum membrane; Multi-pass
CC       membrane protein.
CC   -!- DOMAIN: The histidine box domains may contain the active site and/or be
CC       involved in metal ion binding.
CC   -!- SIMILARITY: Belongs to the fatty acid desaturase type 1 family.
CC       {ECO:0000305}.
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DR   EMBL; D26509; BAA05515.1; -; mRNA.
DR   PIR; JC2555; JC2555.
DR   RefSeq; NP_001311727.1; NM_001324798.1.
DR   AlphaFoldDB; P48626; -.
DR   STRING; 4097.P48626; -.
DR   GeneID; 107763446; -.
DR   KEGG; nta:107763446; -.
DR   OMA; NKCQFVE; -.
DR   PhylomeDB; P48626; -.
DR   BRENDA; 1.14.19.25; 3645.
DR   UniPathway; UPA00658; -.
DR   Proteomes; UP000084051; Unplaced.
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:0016717; F:oxidoreductase activity, acting on paired donors, with oxidation of a pair of donors resulting in the reduction of molecular oxygen to two molecules of water; IEA:InterPro.
DR   GO; GO:0006636; P:unsaturated fatty acid biosynthetic process; IEA:UniProtKB-UniPathway.
DR   InterPro; IPR005804; FA_desaturase_dom.
DR   InterPro; IPR021863; FAS_N.
DR   Pfam; PF11960; DUF3474; 1.
DR   Pfam; PF00487; FA_desaturase; 1.
PE   2: Evidence at transcript level;
KW   Endoplasmic reticulum; Fatty acid biosynthesis; Fatty acid metabolism;
KW   Lipid biosynthesis; Lipid metabolism; Membrane; Oxidoreductase;
KW   Reference proteome; Transmembrane; Transmembrane helix.
FT   CHAIN           1..379
FT                   /note="Omega-3 fatty acid desaturase, endoplasmic
FT                   reticulum"
FT                   /id="PRO_0000185415"
FT   TRANSMEM        52..72
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        213..233
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        236..256
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   MOTIF           97..101
FT                   /note="Histidine box-1"
FT   MOTIF           133..137
FT                   /note="Histidine box-2"
FT   MOTIF           300..304
FT                   /note="Histidine box-3"
SQ   SEQUENCE   379 AA;  44149 MW;  87221A21AB02E1B2 CRC64;
     MGSLGISEIY DKNSFNEMEF EFDPSAPPPF RLAEIRNVIP KHCWVKDPLR SLSYVVRDVI
     FVATLIGIAI HLDSWLFYPL YWAIQGTMFW AIFVLGHDCG HGSFSDSQLL NNVVGHILHS
     AILVPYHGWR ISHKTHHQNH GNVETDESWV PMPEKLYNKV GYSTKFLRYK IPFPLLAYPM
     YLMKRSPGKS GSHFNPYSDL FQPHERKYVV TSTLCWTVMA ALLLYLCTAF GSLQMFKIYG
     APYLIFVMWL DFVTYLHHHG YEKKLPWYRG KEWSYLRGGL TTVDRDYGLF NNIHHDIGTH
     VIHHLFPQIP HYHLREATKA AKPVLGKYYR EPKKSGPIPF HLVKDLTRSM KQDHYVSDSG
     EIVFYQTDPH IFRSAPKDE