ID   3SA5B_NAJSP             Reviewed;          81 AA.
AC   P60310;
DT   02-FEB-2004, integrated into UniProtKB/Swiss-Prot.
DT   02-FEB-2004, sequence version 1.
DT   25-MAY-2022, entry version 65.
DE   RecName: Full=Cytotoxin 5b;
DE   AltName: Full=Cardiotoxin 5b;
DE            Short=CTX-5b;
DE            Short=Ctx5b;
DE   Flags: Precursor;
OS   Naja sputatrix (Malayan spitting cobra) (Naja naja sputatrix).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Elapidae; Elapinae; Naja.
OX   NCBI_TaxID=33626;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   TISSUE=Venom gland;
RX   PubMed=9565688; DOI=10.1016/s0304-4165(97)00143-8;
RA   Jeyaseelan K., Armugam A., Lachumanan R., Tan C.H., Tan N.H.;
RT   "Six isoforms of cardiotoxin in malayan spitting cobra (Naja naja
RT   sputatrix) venom: cloning and characterization of cDNAs.";
RL   Biochim. Biophys. Acta 1380:209-222(1998).
CC   -!- FUNCTION: Shows cytolytic activity on many different cells by forming
CC       pore in lipid membranes. In vivo, increases heart rate or kills the
CC       animal by cardiac arrest. In addition, it binds to heparin with high
CC       affinity, interacts with Kv channel-interacting protein 1 (KCNIP1) in a
CC       calcium-independent manner, and binds to integrin alpha-V/beta-3
CC       (ITGAV/ITGB3) with moderate affinity. {ECO:0000250|UniProtKB:P60301,
CC       ECO:0000250|UniProtKB:P60304}.
CC   -!- SUBUNIT: Monomer in solution; Homodimer and oligomer in the presence of
CC       negatively charged lipids forming a pore with a size ranging between 20
CC       and 30 Angstroms. {ECO:0000250|UniProtKB:P60301}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000250}. Target cell membrane
CC       {ECO:0000250|UniProtKB:P60301}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland. {ECO:0000305}.
CC   -!- MISCELLANEOUS: Is classified as a S-type cytotoxin, since a serine
CC       residue stands at position 49 (Ser-29 in standard classification).
CC       {ECO:0000305}.
CC   -!- SIMILARITY: Belongs to the snake three-finger toxin family. Short-chain
CC       subfamily. Type IA cytotoxin sub-subfamily. {ECO:0000305}.
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DR   EMBL; U86597; AAC27692.1; -; mRNA.
DR   AlphaFoldDB; P60310; -.
DR   SMR; P60310; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0016020; C:membrane; IEA:UniProtKB-KW.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   GO; GO:0019835; P:cytolysis; IEA:UniProtKB-KW.
DR   CDD; cd00206; snake_toxin; 1.
DR   Gene3D; 2.10.60.10; -; 1.
DR   InterPro; IPR003572; Cytotoxin_Cobra.
DR   InterPro; IPR003571; Snake_3FTx.
DR   InterPro; IPR045860; Snake_toxin-like_sf.
DR   InterPro; IPR018354; Snake_toxin_con_site.
DR   PRINTS; PR00282; CYTOTOXIN.
DR   SUPFAM; SSF57302; SSF57302; 1.
DR   PROSITE; PS00272; SNAKE_TOXIN; 1.
PE   3: Inferred from homology;
KW   Cardiotoxin; Cytolysis; Disulfide bond; Membrane; Secreted; Signal;
KW   Target cell membrane; Target membrane; Toxin.
FT   SIGNAL          1..21
FT                   /evidence="ECO:0000250"
FT   CHAIN           22..81
FT                   /note="Cytotoxin 5b"
FT                   /id="PRO_0000035401"
FT   DISULFID        24..42
FT                   /evidence="ECO:0000250|UniProtKB:P60301"
FT   DISULFID        35..59
FT                   /evidence="ECO:0000250|UniProtKB:P60301"
FT   DISULFID        63..74
FT                   /evidence="ECO:0000250|UniProtKB:P60301"
FT   DISULFID        75..80
FT                   /evidence="ECO:0000250|UniProtKB:P60301"
SQ   SEQUENCE   81 AA;  9055 MW;  04CC86FE142B49BA CRC64;
     MKTLLLTLLV VTIVCLDLGY TLKCNKLVPL FYKTCPAGKN LCYKMFMVSN LTVPVKRGCI
     DVCPKNSALV KYVCCNTDRC N