ID   3SA4N_NAJAT             Reviewed;          81 AA.
AC   Q9W6W9;
DT   02-FEB-2004, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1999, sequence version 1.
DT   25-MAY-2022, entry version 71.
DE   RecName: Full=Cytotoxin 4N;
DE   AltName: Full=Cardiotoxin-4N;
DE            Short=CTX-4N;
DE   Flags: Precursor;
OS   Naja atra (Chinese cobra).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Elapidae; Elapinae; Naja.
OX   NCBI_TaxID=8656;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   TISSUE=Liver;
RX   PubMed=15587986; DOI=10.1023/b:bigi.0000043955.35906.c2;
RA   Chang L.-S., Lin S.-K., Chung C.;
RT   "Molecular cloning and evolution of the genes encoding the precursors of
RT   taiwan cobra cardiotoxin and cardiotoxin-like basic protein.";
RL   Biochem. Genet. 42:429-440(2004).
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; AJ238737; CAB42057.1; -; Genomic_DNA.
DR   AlphaFoldDB; Q9W6W9; -.
DR   SMR; Q9W6W9; -.
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 4N"
FT                   /id="PRO_0000035376"
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;  9099 MW;  221274FCE4D72EBE CRC64;
     MKTLLLTLVV VTIVCLDLGY TRKCNKLVPL FYKTCPAGKN LCYKMFMVSN LTVPVKRGCI
     DVCPKSSLLV KYVCCNTDRC N