ID   LDHB_ANAPL              Reviewed;         333 AA.
AC   P13743;
DT   01-JAN-1990, integrated into UniProtKB/Swiss-Prot.
DT   23-JAN-2007, sequence version 2.
DT   03-AUG-2022, entry version 125.
DE   RecName: Full=L-lactate dehydrogenase B chain;
DE            Short=LDH-B;
DE            EC=1.1.1.27 {ECO:0000250|UniProtKB:P07195};
DE   AltName: Full=Epsilon-crystallin;
GN   Name=LDHB;
OS   Anas platyrhynchos (Mallard) (Anas boschas).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Archelosauria; Archosauria; Dinosauria; Saurischia; Theropoda;
OC   Coelurosauria; Aves; Neognathae; Galloanserae; Anseriformes; Anatidae;
OC   Anatinae; Anas.
OX   NCBI_TaxID=8839;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RX   PubMed=3174623; DOI=10.1073/pnas.85.19.7114;
RA   Hendriks W., Mulders J.W.M., Bibby M.A., Slingsby C., Bloemendal H.,
RA   de Jong W.W.;
RT   "Duck lens epsilon-crystallin and lactate dehydrogenase B4 are identical: a
RT   single-copy gene product with two distinct functions.";
RL   Proc. Natl. Acad. Sci. U.S.A. 85:7114-7118(1988).
RN   [2]
RP   PROTEIN SEQUENCE OF 91-112; 119-126; 149-155; 233-243 AND 308-328.
RX   PubMed=3971972; DOI=10.1111/j.1432-1033.1985.tb08728.x;
RA   Stapel S.O., Zweers A., Dodemont H.J., Kan J.H., de Jong W.W.;
RT   "Epsilon-crystallin, a novel avian and reptilian eye lens protein.";
RL   Eur. J. Biochem. 147:129-136(1985).
RN   [3]
RP   EQUIVALENCE OF EPSILON CRYSTALLIN WITH LDH-B.
RX   PubMed=3561501; DOI=10.1038/326622a0;
RA   Wistow G.J., Mulders J.W.M., de Jong W.W.;
RT   "The enzyme lactate dehydrogenase as a structural protein in avian and
RT   crocodilian lenses.";
RL   Nature 326:622-624(1987).
CC   -!- FUNCTION: Interconverts simultaneously and stereospecifically pyruvate
CC       and lactate with concomitant interconversion of NADH and NAD(+).
CC       {ECO:0000250|UniProtKB:P07195}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=(S)-lactate + NAD(+) = H(+) + NADH + pyruvate;
CC         Xref=Rhea:RHEA:23444, ChEBI:CHEBI:15361, ChEBI:CHEBI:15378,
CC         ChEBI:CHEBI:16651, ChEBI:CHEBI:57540, ChEBI:CHEBI:57945; EC=1.1.1.27;
CC         Evidence={ECO:0000250|UniProtKB:P07195};
CC       PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:23445;
CC         Evidence={ECO:0000250|UniProtKB:P07195};
CC       PhysiologicalDirection=right-to-left; Xref=Rhea:RHEA:23446;
CC         Evidence={ECO:0000250|UniProtKB:P07195};
CC   -!- PATHWAY: Fermentation; pyruvate fermentation to lactate; (S)-lactate
CC       from pyruvate: step 1/1. {ECO:0000250|UniProtKB:P07195}.
CC   -!- SUBUNIT: Homotetramer.
CC   -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the LDH/MDH superfamily. LDH family.
CC       {ECO:0000305}.
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DR   EMBL; J03869; AAA49221.1; -; mRNA.
DR   PIR; A21986; A21986.
DR   PIR; A40488; A40488.
DR   AlphaFoldDB; P13743; -.
DR   SMR; P13743; -.
DR   MoonProt; P13743; -.
DR   SABIO-RK; P13743; -.
DR   UniPathway; UPA00554; UER00611.
DR   GO; GO:0005737; C:cytoplasm; IEA:UniProtKB-SubCell.
DR   GO; GO:0004459; F:L-lactate dehydrogenase activity; IEA:UniProtKB-EC.
DR   GO; GO:0005212; F:structural constituent of eye lens; IEA:UniProtKB-KW.
DR   GO; GO:0019752; P:carboxylic acid metabolic process; IEA:InterPro.
DR   Gene3D; 3.90.110.10; -; 1.
DR   HAMAP; MF_00488; Lactate_dehydrog; 1.
DR   InterPro; IPR001557; L-lactate/malate_DH.
DR   InterPro; IPR011304; L-lactate_DH.
DR   InterPro; IPR018177; L-lactate_DH_AS.
DR   InterPro; IPR022383; Lactate/malate_DH_C.
DR   InterPro; IPR001236; Lactate/malate_DH_N.
DR   InterPro; IPR015955; Lactate_DH/Glyco_Ohase_4_C.
DR   InterPro; IPR036291; NAD(P)-bd_dom_sf.
DR   Pfam; PF02866; Ldh_1_C; 1.
DR   Pfam; PF00056; Ldh_1_N; 1.
DR   PIRSF; PIRSF000102; Lac_mal_DH; 1.
DR   PRINTS; PR00086; LLDHDRGNASE.
DR   SUPFAM; SSF51735; SSF51735; 1.
DR   SUPFAM; SSF56327; SSF56327; 1.
DR   TIGRFAMs; TIGR01771; L-LDH-NAD; 1.
DR   PROSITE; PS00064; L_LDH; 1.
PE   1: Evidence at protein level;
KW   Cytoplasm; Direct protein sequencing; Eye lens protein; NAD;
KW   Oxidoreductase.
FT   INIT_MET        1
FT                   /note="Removed"
FT   CHAIN           2..333
FT                   /note="L-lactate dehydrogenase B chain"
FT                   /id="PRO_0000168465"
FT   ACT_SITE        193
FT                   /note="Proton acceptor"
FT                   /evidence="ECO:0000250"
FT   BINDING         29..57
FT                   /ligand="NAD(+)"
FT                   /ligand_id="ChEBI:CHEBI:57540"
FT                   /evidence="ECO:0000250"
FT   BINDING         99
FT                   /ligand="NAD(+)"
FT                   /ligand_id="ChEBI:CHEBI:57540"
FT                   /evidence="ECO:0000250"
FT   BINDING         106
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
FT   BINDING         138
FT                   /ligand="NAD(+)"
FT                   /ligand_id="ChEBI:CHEBI:57540"
FT                   /evidence="ECO:0000250"
FT   BINDING         138
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
FT   BINDING         169
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
FT   BINDING         248
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   333 AA;  36090 MW;  6489EA67D5EA560E CRC64;
     MATLKEKLMT PVAAASAVPS SKITVVGVGQ VGMACAVSIL GKGLCDELAL VDVLEDKLKG
     EMMDLQHGSL FLQTHKIVAD KDYAVTANSK IVVVTAGVRQ QEGESRLNLV QRNVGVFKGI
     IPQIVKYSPN CTILVVSNPV DILTYVTWKL SGLPKHRVIG SGCNLDTARF RYLMAERLGI
     HPTSCHGWIL GEHGDSSVAV WSGVNVAGVS LQELNPAMGT DKDSENWKEV HKQVVESAYE
     VIRLKGYTNW AIGLSVAELC ETMLKNLCRV HSVSTLVKGT YGIENDVFLS LPCVLSASGL
     TSVINQKLKD DEVAQLKKSA DTLWSIQKDL KDM