ID   CAS1_CUCPE              Reviewed;         766 AA.
AC   Q6BE25;
DT   19-OCT-2011, integrated into UniProtKB/Swiss-Prot.
DT   13-SEP-2004, sequence version 1.
DT   25-MAY-2022, entry version 51.
DE   RecName: Full=Cycloartenol synthase;
DE            EC=5.4.99.8;
GN   Name=CPX;
OS   Cucurbita pepo (Vegetable marrow) (Summer squash).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   rosids; fabids; Cucurbitales; Cucurbitaceae; Cucurbiteae; Cucurbita.
OX   NCBI_TaxID=3663;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], FUNCTION, AND CATALYTIC ACTIVITY.
RX   DOI=10.1016/j.tet.2004.04.088;
RA   Shibuya M., Adachi S., Ebizuka Y.;
RT   "Cucurbitadienol synthase, the first committed enzyme for cucurbitacin
RT   biosynthesis, is a distinct enzyme from cycloartenol synthase for
RT   phytosterol biosynthesis.";
RL   Tetrahedron 60:6995-7003(2004).
CC   -!- FUNCTION: Oxidosqualene cyclase involved in the biosynthesis of
CC       cycloartenol. {ECO:0000269|Ref.1}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=(S)-2,3-epoxysqualene = cycloartenol; Xref=Rhea:RHEA:21308,
CC         ChEBI:CHEBI:15441, ChEBI:CHEBI:17030; EC=5.4.99.8;
CC         Evidence={ECO:0000269|Ref.1};
CC   -!- SIMILARITY: Belongs to the terpene cyclase/mutase family.
CC       {ECO:0000305}.
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DR   EMBL; AB116237; BAD34644.1; -; mRNA.
DR   AlphaFoldDB; Q6BE25; -.
DR   SMR; Q6BE25; -.
DR   GO; GO:0005811; C:lipid droplet; IEA:InterPro.
DR   GO; GO:0016871; F:cycloartenol synthase activity; IDA:UniProtKB.
DR   GO; GO:0016104; P:triterpenoid biosynthetic process; IEA:InterPro.
DR   CDD; cd02892; SQCY_1; 1.
DR   InterPro; IPR032696; SQ_cyclase_C.
DR   InterPro; IPR032697; SQ_cyclase_N.
DR   InterPro; IPR018333; Squalene_cyclase.
DR   InterPro; IPR002365; Terpene_synthase_CS.
DR   InterPro; IPR008930; Terpenoid_cyclase/PrenylTrfase.
DR   PANTHER; PTHR11764; PTHR11764; 1.
DR   Pfam; PF13243; SQHop_cyclase_C; 1.
DR   Pfam; PF13249; SQHop_cyclase_N; 1.
DR   SFLD; SFLDG01016; Prenyltransferase_Like_2; 1.
DR   SUPFAM; SSF48239; SSF48239; 2.
DR   TIGRFAMs; TIGR01787; squalene_cyclas; 1.
DR   PROSITE; PS01074; TERPENE_SYNTHASES; 1.
PE   1: Evidence at protein level;
KW   Isomerase; Repeat.
FT   CHAIN           1..766
FT                   /note="Cycloartenol synthase"
FT                   /id="PRO_0000412985"
FT   REPEAT          155..196
FT                   /note="PFTB 1"
FT   REPEAT          520..565
FT                   /note="PFTB 2"
FT   REPEAT          597..637
FT                   /note="PFTB 3"
FT   REPEAT          646..687
FT                   /note="PFTB 4"
FT   ACT_SITE        491
FT                   /note="Proton donor"
FT                   /evidence="ECO:0000250|UniProtKB:P48449"
SQ   SEQUENCE   766 AA;  87364 MW;  C01270A357B60007 CRC64;
     MWQLKIGADT VPSDPSNAGG WLSTLNNHVG RQVWHFHPEL GSPEDLQQIQ QARQHFSDHR
     FEKKHSADLL MRMQFAKENS SFVNLPQVKV KDKEDVTEEA VTRTLRRAIN FYSTIQADDG
     HWPGDYGGPM FLIPGLVITL SITGALNAVL STEHQREICR YLYNHQNKDG GWGLHIEGPS
     TMFGSVLNYV TLRLLGEEAE DGQGAVDKAR KWILDHGGAA AITSWGKMWL SVLGVYEWAG
     NNPLPPELWL LPYLLPCHPG RMWCHCRMVY LPMCYLYGKR FVGPITPIIR SLRKELYLVP
     YHEVDWNKAR NQCAKEDLYY PHPLVQDILW ATLHHVYEPL FMHWPAKRLR EKALQSVMQH
     IHYEDENTRY ICIGPVNKVL NMLCCWAEDP HSEAFKLHIP RIYDYLWIAE DGMKMQGYNG
     SQLWDTAFAV QAIISTELAE EYETTLRKAH KYIKDSQVLE DCPGDLQSWY RHISKGAWPF
     STADHGWPIS DCTAEGLKAV LLLSKLPSEI VGKSIDEQQL YNAVNVILSL QNTDGGFATY
     ELTRSYRWLE LMNPAETFGD IVIDYPYVEC SSAAIQALAA FKKLYPGHRR DEIDNCIAEA
     ADFIESIQAT DGSWYGSWGV CFTYGGWFGI RGLVAAGRRY NNCSSLRKAC DFLLSKELAA
     GGWGESYLSC QNKVYTNIKD DRPHIVNTGW AMLSLIDAGQ SERDPTPLHR AARVLINSQM
     EDGDFPQEEI MGVFNKNCMI SYSAYRNIFP IWALGEYRSR VLKPLK