ID   3SADB_NAJAT             Reviewed;          60 AA.
AC   P60306;
DT   02-FEB-2004, integrated into UniProtKB/Swiss-Prot.
DT   02-FEB-2004, sequence version 1.
DT   03-AUG-2022, entry version 64.
DE   RecName: Full=Cytotoxin SP13b;
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   PROTEIN SEQUENCE, AND SUBCELLULAR LOCATION.
RC   TISSUE=Venom;
RX   PubMed=10708798; DOI=10.1016/s0041-0101(99)00218-4;
RA   Chang L.-S., Huang H.-B., Lin S.-R.;
RT   "The multiplicity of cardiotoxins from Naja naja atra (Taiwan cobra)
RT   venom.";
RL   Toxicon 38:1065-1076(2000).
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:0000269|PubMed:10708798}. Target
CC       cell membrane {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 28 (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}.
CC   ---------------------------------------------------------------------------
CC   Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms
CC   Distributed under the Creative Commons Attribution (CC BY 4.0) License
CC   ---------------------------------------------------------------------------
DR   AlphaFoldDB; P60306; -.
DR   SMR; P60306; -.
DR   PRIDE; P60306; -.
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   1: Evidence at protein level;
KW   Cardiotoxin; Cytolysis; Direct protein sequencing; Disulfide bond;
KW   Membrane; Secreted; Target cell membrane; Target membrane; Toxin.
FT   CHAIN           1..60
FT                   /note="Cytotoxin SP13b"
FT                   /evidence="ECO:0000269|PubMed:10708798"
FT                   /id="PRO_0000093481"
FT   DISULFID        3..21
FT                   /evidence="ECO:0000250|UniProtKB:P60301"
FT   DISULFID        14..38
FT                   /evidence="ECO:0000250|UniProtKB:P60301"
FT   DISULFID        42..53
FT                   /evidence="ECO:0000250|UniProtKB:P60301"
FT   DISULFID        54..59
FT                   /evidence="ECO:0000250|UniProtKB:P60301"
SQ   SEQUENCE   60 AA;  6792 MW;  26054E8C00BEC854 CRC64;
     LKCNKLKPLA YKTCPAGKNL CYKMFMMSNK TVPVKRGCID VCPKNSLLVK YVCCNTDRCN