ID   PA2H4_BOTAS             Reviewed;          23 AA.
AC   Q9PRT7;
DT   05-DEC-2001, integrated into UniProtKB/Swiss-Prot.
DT   01-MAY-2000, sequence version 1.
DT   25-MAY-2022, entry version 48.
DE   RecName: Full=Phospholipase A2 homolog 4 {ECO:0000305};
DE            Short=svPLA2 homolog;
DE   AltName: Full=Myotoxin IV {ECO:0000303|PubMed:7749580};
DE   Flags: Fragment;
OS   Bothrops asper (Terciopelo).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Viperidae; Crotalinae; Bothrops.
OX   NCBI_TaxID=8722;
RN   [1]
RP   PROTEIN SEQUENCE, FUNCTION, AND SUBCELLULAR LOCATION.
RC   TISSUE=Venom;
RX   PubMed=7749580; DOI=10.1002/nt.2620030107;
RA   Diaz C., Lomonte B., Zamudio F., Gutierrez J.M.;
RT   "Purification and characterization of myotoxin IV, a phospholipase A2
RT   variant, from Bothrops asper snake venom.";
RL   Nat. Toxins 3:26-31(1995).
CC   -!- FUNCTION: Snake venom phospholipase A2 homolog that lacks enzymatic
CC       activity (PubMed:7749580). Induces acute muscle damage after
CC       intramuscular injection in mice and disrupts negatively charged
CC       liposomes but not positively charged ones (PubMed:7749580). Also exerts
CC       a weak anticoagulant effect only at concentrations of 40 ug/ml or
CC       higher (PubMed:7749580). A model of myotoxic mechanism has been
CC       proposed: an apo Lys49-PLA2 is activated by the entrance of a
CC       hydrophobic molecule (e.g. fatty acid) at the hydrophobic channel of
CC       the protein leading to a reorientation of a monomer (By similarity).
CC       This reorientation causes a transition between 'inactive' to 'active'
CC       states, causing alignment of C-terminal and membrane-docking sites
CC       (MDoS) side-by-side and putting the membrane-disruption sites (MDiS) in
CC       the same plane, exposed to solvent and in a symmetric position for both
CC       monomers (By similarity). The MDoS region stabilizes the toxin on
CC       membrane by the interaction of charged residues with phospholipid head
CC       groups (By similarity). Subsequently, the MDiS region destabilizes the
CC       membrane with penetration of hydrophobic residues (By similarity). This
CC       insertion causes a disorganization of the membrane, allowing an
CC       uncontrolled influx of ions (i.e. calcium and sodium), and eventually
CC       triggering irreversible intracellular alterations and cell death (By
CC       similarity). {ECO:0000250|UniProtKB:I6L8L6,
CC       ECO:0000269|PubMed:7749580}.
CC   -!- SUBUNIT: Homodimer; non-covalently linked (probable alternative/compact
CC       dimer conformation in solution). {ECO:0000250|UniProtKB:I6L8L6}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:7749580}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC       {ECO:0000305|PubMed:7749580}.
CC   -!- SIMILARITY: Belongs to the phospholipase A2 family. Group II subfamily.
CC       K49 sub-subfamily. {ECO:0000305}.
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DR   AlphaFoldDB; Q9PRT7; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
PE   1: Evidence at protein level;
KW   Blood coagulation cascade inhibiting toxin; Direct protein sequencing;
KW   Hemostasis impairing toxin; Myotoxin; Secreted; Toxin.
FT   CHAIN           1..>23
FT                   /note="Phospholipase A2 homolog 4"
FT                   /id="PRO_0000161619"
FT   NON_TER         23
SQ   SEQUENCE   23 AA;  2512 MW;  8D84B07051C6D250 CRC64;
     SLVELGKMIL QETGKNPVTY GAY