ID   CFI2_PETHY              Reviewed;         220 AA.
AC   P11651;
DT   01-OCT-1989, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-1989, sequence version 1.
DT   03-AUG-2022, entry version 88.
DE   RecName: Full=Chalcone--flavanone isomerase B;
DE            Short=CHI-B;
DE            Short=Chalcone isomerase B;
DE            EC=5.5.1.6;
GN   Name=CHI2; Synonyms=CHIB;
OS   Petunia hybrida (Petunia).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   asterids; lamiids; Solanales; Solanaceae; Petunioideae; Petunia.
OX   NCBI_TaxID=4102;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=cv. Violet 30; TISSUE=Leaf;
RA   van Tunen A.J., Hartman S.A., Mur L.A., Mol J.N.M.;
RT   "Regulation of chalone flavanone isomerase (CHI) gene expression in Petunia
RT   hybrida: the use of alternative promoters in corolla anthers and pollen.";
RL   Plant Mol. Biol. 12:539-551(1989).
CC   -!- FUNCTION: Catalyzes the intramolecular cyclization of bicyclic
CC       chalcones into tricyclic (S)-flavanones. Responsible for the
CC       isomerization of 4,2',4',6'-tetrahydroxychalcone (also termed chalcone)
CC       into naringenin (By similarity). {ECO:0000250}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=a chalcone = a flavanone.; EC=5.5.1.6;
CC   -!- PATHWAY: Secondary metabolite biosynthesis; flavonoid biosynthesis.
CC   -!- MISCELLANEOUS: Part of the biosynthetic pathway for all classes of
CC       flavonoids, a large class of secondary plant metabolites, many of which
CC       are brightly colored.
CC   -!- SIMILARITY: Belongs to the chalcone isomerase family. {ECO:0000305}.
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DR   EMBL; X14590; CAA32730.1; -; Genomic_DNA.
DR   PIR; S04726; ISPJCB.
DR   AlphaFoldDB; P11651; -.
DR   SMR; P11651; -.
DR   UniPathway; UPA00154; -.
DR   GO; GO:0045430; F:chalcone isomerase activity; IEA:UniProtKB-EC.
DR   GO; GO:0009813; P:flavonoid biosynthetic process; IEA:UniProtKB-UniPathway.
DR   Gene3D; 1.10.890.20; -; 1.
DR   Gene3D; 3.50.70.10; -; 1.
DR   InterPro; IPR044164; CFI.
DR   InterPro; IPR016087; Chalcone_isomerase.
DR   InterPro; IPR016088; Chalcone_isomerase_3-sand.
DR   InterPro; IPR016089; Chalcone_isomerase_bundle_sf.
DR   InterPro; IPR036298; Chalcone_isomerase_sf.
DR   PANTHER; PTHR28039; PTHR28039; 1.
DR   Pfam; PF02431; Chalcone; 1.
DR   SUPFAM; SSF54626; SSF54626; 1.
PE   3: Inferred from homology;
KW   Flavonoid biosynthesis; Isomerase.
FT   CHAIN           1..220
FT                   /note="Chalcone--flavanone isomerase B"
FT                   /id="PRO_0000166438"
FT   BINDING         50
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
FT   BINDING         115
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
FT   BINDING         192
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   220 AA;  23944 MW;  F6A7433CF9A517FF CRC64;
     MSPSVSVTKV QVENYVFPPT VKPPASTKTL FLGGAGHRGL DVEGKFVKFT VIGVYLEESA
     VQFLAPKWKG KSAEELIHSV DFFRDIVTGP FEKFTRVRFI LPLTGKQFSE KVAENCVAHW
     KATGTYSDAG SRAIEKFLNV VKSETFLPGA SILFTQSPLG SLTISFTKDD SISEAGNAVI
     ENKQFSEAVL ETIIGEHGVS PAAKCSIAAR MSELFKNSLF