ID   LDHB_SQUAC              Reviewed;         334 AA.
AC   Q9YI05;
DT   01-JUN-2001, integrated into UniProtKB/Swiss-Prot.
DT   01-MAY-1999, sequence version 1.
DT   03-AUG-2022, entry version 101.
DE   RecName: Full=L-lactate dehydrogenase B chain;
DE            Short=LDH-B;
DE            EC=1.1.1.27 {ECO:0000250|UniProtKB:P07195};
GN   Name=ldhb;
OS   Squalus acanthias (Spiny dogfish).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Chondrichthyes;
OC   Elasmobranchii; Squalomorphii; Squaliformes; Squalidae; Squalus.
OX   NCBI_TaxID=7797;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   TISSUE=Heart muscle;
RX   PubMed=9628010;
RA   Stock D.W., Powers D.A.;
RT   "A monophyletic origin of heart-predominant lactate dehydrogenase (LDH)
RT   isozymes of gnathostome vertebrates: evidence from the cDNA sequence of the
RT   spiny dogfish (Squalus acanthias) LDH-B.";
RL   Mol. Mar. Biol. Biotechnol. 7:160-164(1998).
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. {ECO:0000250}.
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; AF059035; AAD02703.1; -; mRNA.
DR   AlphaFoldDB; Q9YI05; -.
DR   SMR; Q9YI05; -.
DR   PRIDE; Q9YI05; -.
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: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   2: Evidence at transcript level;
KW   Cytoplasm; NAD; Oxidoreductase.
FT   CHAIN           1..334
FT                   /note="L-lactate dehydrogenase B chain"
FT                   /id="PRO_0000168478"
FT   ACT_SITE        194
FT                   /note="Proton acceptor"
FT                   /evidence="ECO:0000250"
FT   BINDING         30..58
FT                   /ligand="NAD(+)"
FT                   /ligand_id="ChEBI:CHEBI:57540"
FT                   /evidence="ECO:0000250"
FT   BINDING         100
FT                   /ligand="NAD(+)"
FT                   /ligand_id="ChEBI:CHEBI:57540"
FT                   /evidence="ECO:0000250"
FT   BINDING         107
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
FT   BINDING         139
FT                   /ligand="NAD(+)"
FT                   /ligand_id="ChEBI:CHEBI:57540"
FT                   /evidence="ECO:0000250"
FT   BINDING         139
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
FT   BINDING         170
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
FT   BINDING         249
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   334 AA;  36833 MW;  03B43D9B784474D5 CRC64;
     MATVQQKLIT PVSQERSDAS RNKVTVVGVG QVGMACAVSI LLRELTDEIA LVDVLEDKLK
     GEMMDLLHGS LFLKTPKIMA NKDYGITANS RVVVVTAGAR QQEGESRLNL VQRNVNIFKF
     IIPQIVKYSP NCTIIVVSNP VDILTYVTWK ISGFPKNRVI GSGCNLDSAR FRYLMAEKLG
     LHPSSCHGWV LGEHGDSSVP VWSGVNVAGV GLQQLNPDIG TAQDKENWKD VHKMVVESAY
     EVIKLKGYTN WAIGLSVAEL TESMVKNLKR VHPVSTMVKG MYGIENEVFL SLPCVLSADG
     LIDVINQMLK DDEVAQLRKS AETLWNIQKE LKDL