ID   3SA3_NAJNA              Reviewed;          60 AA.
AC   P24780;
DT   01-MAR-1992, integrated into UniProtKB/Swiss-Prot.
DT   01-MAR-1992, sequence version 1.
DT   03-AUG-2022, entry version 83.
DE   RecName: Full=Cytotoxin 3;
DE   AltName: Full=Cytotoxin IIa;
OS   Naja naja (Indian cobra).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Elapidae; Elapinae; Naja.
OX   NCBI_TaxID=35670;
RN   [1]
RP   PROTEIN SEQUENCE, SUBCELLULAR LOCATION, AND TOXIC DOSE.
RC   TISSUE=Venom;
RX   PubMed=6525197;
RA   Kaneda N., Takechi M., Sasaki T., Hayashi K.;
RT   "Amino acid sequence of cytotoxin IIa isolated from the venom of the Indian
RT   cobra (Naja naja).";
RL   Biochem. Int. 9:603-610(1984).
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:6525197}. Target
CC       cell membrane {ECO:0000250|UniProtKB:P60301}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland. {ECO:0000305}.
CC   -!- TOXIC DOSE: LD(50) is 40 to 55 mg/kg by subcutaneous injection.
CC       {ECO:0000269|PubMed:6525197}.
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}.
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DR   AlphaFoldDB; P24780; -.
DR   SMR; P24780; -.
DR   Proteomes; UP000694559; Unplaced.
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; Reference proteome; Secreted; Target cell membrane;
KW   Target membrane; Toxin.
FT   CHAIN           1..60
FT                   /note="Cytotoxin 3"
FT                   /evidence="ECO:0000269|PubMed:6525197"
FT                   /id="PRO_0000093512"
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;  6745 MW;  84125AC1BE4F45E2 CRC64;
     LKCNKLIPLA YKTCPAGKNL CYKMFMVSNK TVPVKRGCID VCPKNSLVLK YVCCNTDRCN