ID   FDFT_NICBE              Reviewed;         411 AA.
AC   P53800;
DT   01-OCT-1996, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-1996, sequence version 1.
DT   25-MAY-2022, entry version 100.
DE   RecName: Full=Squalene synthase;
DE            Short=SQS;
DE            Short=SS;
DE            EC=2.5.1.21;
DE   AltName: Full=FPP:FPP farnesyltransferase;
DE   AltName: Full=Farnesyl-diphosphate farnesyltransferase;
OS   Nicotiana benthamiana.
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   asterids; lamiids; Solanales; Solanaceae; Nicotianoideae; Nicotianeae;
OC   Nicotiana.
OX   NCBI_TaxID=4100;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RX   PubMed=8704125; DOI=10.1007/bf00019548;
RA   Hanley K.M., Nicolas O., Donaldson T.B., Smith-Monroy C., Robinson G.W.,
RA   Hellmann G.M.;
RT   "Molecular cloning, in vitro expression and characterization of a plant
RT   squalene synthetase cDNA.";
RL   Plant Mol. Biol. 30:1139-1151(1996).
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=2 (2E,6E)-farnesyl diphosphate + H(+) + NADPH = 2 diphosphate
CC         + NADP(+) + squalene; Xref=Rhea:RHEA:32295, ChEBI:CHEBI:15378,
CC         ChEBI:CHEBI:15440, ChEBI:CHEBI:33019, ChEBI:CHEBI:57783,
CC         ChEBI:CHEBI:58349, ChEBI:CHEBI:175763; EC=2.5.1.21;
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=2 (2E,6E)-farnesyl diphosphate + H(+) + NADH = 2 diphosphate +
CC         NAD(+) + squalene; Xref=Rhea:RHEA:32299, ChEBI:CHEBI:15378,
CC         ChEBI:CHEBI:15440, ChEBI:CHEBI:33019, ChEBI:CHEBI:57540,
CC         ChEBI:CHEBI:57945, ChEBI:CHEBI:175763; EC=2.5.1.21;
CC   -!- COFACTOR:
CC       Name=Mg(2+); Xref=ChEBI:CHEBI:18420; Evidence={ECO:0000250};
CC   -!- PATHWAY: Terpene metabolism; lanosterol biosynthesis; lanosterol from
CC       farnesyl diphosphate: step 1/3.
CC   -!- SUBCELLULAR LOCATION: Endoplasmic reticulum membrane {ECO:0000250};
CC       Multi-pass membrane protein {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the phytoene/squalene synthase family.
CC       {ECO:0000305}.
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DR   EMBL; U46000; AAA87048.1; -; mRNA.
DR   PIR; S71771; S71771.
DR   AlphaFoldDB; P53800; -.
DR   SMR; P53800; -.
DR   UniPathway; UPA00767; UER00751.
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:0004310; F:farnesyl-diphosphate farnesyltransferase activity; IEA:UniProtKB-EC.
DR   GO; GO:0051996; F:squalene synthase activity; IEA:UniProtKB-EC.
DR   GO; GO:0008299; P:isoprenoid biosynthetic process; IEA:UniProtKB-KW.
DR   CDD; cd00683; Trans_IPPS_HH; 1.
DR   Gene3D; 1.10.600.10; -; 1.
DR   InterPro; IPR008949; Isoprenoid_synthase_dom_sf.
DR   InterPro; IPR002060; Squ/phyt_synthse.
DR   InterPro; IPR006449; Squal_synth-like.
DR   InterPro; IPR019845; Squalene/phytoene_synthase_CS.
DR   InterPro; IPR044844; Trans_IPPS_euk-type.
DR   InterPro; IPR033904; Trans_IPPS_HH.
DR   PANTHER; PTHR11626; PTHR11626; 1.
DR   Pfam; PF00494; SQS_PSY; 1.
DR   SFLD; SFLDG01018; Squalene/Phytoene_Synthase_Lik; 1.
DR   SUPFAM; SSF48576; SSF48576; 1.
DR   TIGRFAMs; TIGR01559; squal_synth; 1.
DR   PROSITE; PS01044; SQUALEN_PHYTOEN_SYN_1; 1.
DR   PROSITE; PS01045; SQUALEN_PHYTOEN_SYN_2; 1.
PE   2: Evidence at transcript level;
KW   Endoplasmic reticulum; Isoprene biosynthesis; Magnesium; Membrane;
KW   Multifunctional enzyme; NADP; Transferase; Transmembrane;
KW   Transmembrane helix.
FT   CHAIN           1..411
FT                   /note="Squalene synthase"
FT                   /id="PRO_0000067456"
FT   TRANSMEM        281..301
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        388..408
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
SQ   SEQUENCE   411 AA;  47083 MW;  5DE209E9BB70A42A CRC64;
     MGSLRAILKN PEDLYPLVKL KLAARHAEKQ IPPSPNWGFC YSMLHKVSRS FALVIQQLPV
     ELRDAVCIFY LVLRALDTVE DDTSIPTDVK VPILISFHQH VYDREWHFSC GTKEYKVLMD
     QFHHVSTAFL ELRKHYQQAI EDITMRMGAG MAKFICKEVE TTDDYDEYCH YVAGLVGLGL
     SKLFHASEKE DLASDSLSNS MGLFLQKTNI IRDYLEDINE VPKCRMFWPR EIWSKYVNKL
     EELKYEDNSA KAVQCLNDMV TNALPHVEDC LTYMSALRDP SIFRFCAIPQ VMAIGTLAMC
     YDNIEVFRGV VKMRRGLTAK VIDRTRTIAD VYGAFFDFSC MLKSKVNNND PNATKTLKRL
     EVILKTCRDS GTLNKRKSYI IRSEPNYSPV LIVVIFIILA IILAQLSGNR S