ID   KCRB_SQUAC              Reviewed;          52 AA.
AC   P26460;
DT   01-AUG-1992, integrated into UniProtKB/Swiss-Prot.
DT   01-AUG-1992, sequence version 1.
DT   02-SEP-2026, entry version 96.
DE   RecName: Full=Creatine kinase B-type {ECO:0000305};
DE            EC=2.7.3.2 {ECO:0000250|UniProtKB:P12277};
DE   AltName: Full=B-CK {ECO:0000305};
DE   AltName: Full=Creatine kinase B chain {ECO:0000305};
DE   Flags: Fragments;
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   PROTEIN SEQUENCE, SUBCELLULAR LOCATION, AND TISSUE SPECIFICITY.
RC   TISSUE=Rectal gland;
RX   PubMed=1310991; DOI=10.1016/s0021-9258(19)50655-x;
RA   Friedman D.L., Roberts R.;
RT   "Purification and localization of brain-type creatine kinase in sodium
RT   chloride transporting epithelia of the spiny dogfish, Squalus acanthias.";
RL   J. Biol. Chem. 267:4270-4276(1992).
CC   -!- FUNCTION: Reversibly catalyzes the transfer of phosphate between ATP
CC       and various phosphogens (e.g. creatine phosphate). Creatine kinase
CC       isoenzymes play a central role in energy transduction in tissues with
CC       large, fluctuating energy demands, such as skeletal muscle, heart,
CC       brain and spermatozoa. {ECO:0000250|UniProtKB:P12277}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=creatine + ATP = N-phosphocreatine + ADP + H(+);
CC         Xref=Rhea:RHEA:17157, ChEBI:CHEBI:15378, ChEBI:CHEBI:30616,
CC         ChEBI:CHEBI:57947, ChEBI:CHEBI:58092, ChEBI:CHEBI:456216; EC=2.7.3.2;
CC         Evidence={ECO:0000250|UniProtKB:P12277, ECO:0000255|PROSITE-
CC         ProRule:PRU10029};
CC   -!- SUBUNIT: Dimer of identical or non-identical chains, which can be
CC       either B (brain type) or M (muscle type). With MM being the major form
CC       in skeletal muscle and myocardium, MB existing in myocardium, and BB
CC       existing in many tissues, especially brain.
CC       {ECO:0000250|UniProtKB:P12277}.
CC   -!- SUBCELLULAR LOCATION: Cytoplasm, cytosol
CC       {ECO:0000250|UniProtKB:Q04447}. Mitochondrion
CC       {ECO:0000250|UniProtKB:Q04447}. Basal cell membrane
CC       {ECO:0000269|PubMed:1310991}. Note=Basal membrane of the sodium
CC       chloride-secreting epithelia. {ECO:0000269|PubMed:1310991}.
CC   -!- TISSUE SPECIFICITY: Expressed in rectal gland, brain, skeletal muscle
CC       (at protein level). {ECO:0000269|PubMed:1310991}.
CC   -!- SIMILARITY: Belongs to the ATP:guanido phosphotransferase family.
CC       {ECO:0000255|PROSITE-ProRule:PRU00842, ECO:0000255|PROSITE-
CC       ProRule:PRU00843}.
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DR   PIR; A42272; A42272.
DR   PIR; B42272; B42272.
DR   GO; GO:0009925; C:basal plasma membrane; EXP:UniProtKB.
DR   GO; GO:0005829; C:cytosol; IEA:UniProtKB-SubCell.
DR   GO; GO:0005739; C:mitochondrion; ISS:UniProtKB.
DR   GO; GO:0004111; F:creatine kinase activity; ISS:UniProtKB.
DR   GO; GO:0046314; P:phosphocreatine biosynthetic process; IEA:InterPro.
DR   Gene3D; 1.10.135.10; ATP:guanido phosphotransferase, N-terminal domain; 1.
DR   InterPro; IPR000749; ATP-guanido_PTrfase.
DR   InterPro; IPR022415; ATP-guanido_PTrfase_AS.
DR   InterPro; IPR022414; ATP-guanido_PTrfase_cat.
DR   InterPro; IPR022413; ATP-guanido_PTrfase_N.
DR   InterPro; IPR036802; ATP-guanido_PTrfase_N_sf.
DR   InterPro; IPR014746; Gln_synth/guanido_kin_cat_dom.
DR   PANTHER; PTHR11547; ARGININE OR CREATINE KINASE; 1.
DR   PANTHER; PTHR11547:SF23; CREATINE KINASE B-TYPE; 1.
DR   Pfam; PF02807; ATP-gua_PtransN; 1.
DR   SUPFAM; SSF55931; Glutamine synthetase/guanido kinase; 1.
DR   SUPFAM; SSF48034; Guanido kinase N-terminal domain; 1.
DR   PROSITE; PS00112; PHOSPHAGEN_KINASE; 1.
DR   PROSITE; PS51510; PHOSPHAGEN_KINASE_C; 1.
DR   PROSITE; PS51509; PHOSPHAGEN_KINASE_N; 1.
PE   1: Evidence at protein level;
KW   ATP-binding; Cell membrane; Cytoplasm; Direct protein sequencing; Kinase;
KW   Membrane; Mitochondrion; Nucleotide-binding; Transferase.
FT   CHAIN           <1..>52
FT                   /note="Creatine kinase B-type"
FT                   /id="PRO_0000211972"
FT   DOMAIN          1..52
FT                   /note="Phosphagen kinase C-terminal"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00843"
FT   DOMAIN          1..52
FT                   /note="Phosphagen kinase N-terminal"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00842"
FT   BINDING         13
FT                   /ligand="ATP"
FT                   /ligand_id="ChEBI:CHEBI:30616"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00843"
FT   BINDING         47
FT                   /ligand="ATP"
FT                   /ligand_id="ChEBI:CHEBI:30616"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00843"
FT   VARIANT         3
FT                   /note="V -> I"
FT   VARIANT         5
FT                   /note="T -> S"
FT   VARIANT         10
FT                   /note="K -> S"
FT   VARIANT         13
FT                   /note="R -> K"
FT   VARIANT         16
FT                   /note="S -> Q"
FT   UNSURE          38
FT   NON_CONS        28..29
FT                   /evidence="ECO:0000305"
FT   NON_TER         1
FT                   /evidence="ECO:0000269|PubMed:1310991"
FT   NON_TER         52
FT                   /evidence="ECO:0000269|PubMed:1310991"
SQ   SEQUENCE   52 AA;  5778 MW;  3BC2C989F21CFF30 CRC64;
     AKVLTLDLYK KLRDKSTPSG FTLDDIIQNE HLGYVLTCPS NLGTXLRAXV HV
//