ID   SLB_ECHCS               Reviewed;         123 AA.
AC   P81996;
DT   30-MAY-2000, integrated into UniProtKB/Swiss-Prot.
DT   30-MAY-2000, sequence version 1.
DT   25-MAY-2022, entry version 78.
DE   RecName: Full=Snaclec echicetin subunit beta;
OS   Echis carinatus sochureki (Saw-scaled viper).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Viperidae; Viperinae; Echis.
OX   NCBI_TaxID=124223;
RN   [1]
RP   PROTEIN SEQUENCE, AND SUBCELLULAR LOCATION.
RC   TISSUE=Venom;
RX   PubMed=7999097; DOI=10.1006/bbrc.1994.2630;
RA   Peng M., Holt J.C., Niewiarowski S.;
RT   "Isolation, characterization and amino acid sequence of echicetin beta
RT   subunit, a specific inhibitor of von Willebrand factor and thrombin
RT   interaction with glycoprotein Ib.";
RL   Biochem. Biophys. Res. Commun. 205:68-72(1994).
RN   [2]
RP   PROTEIN SEQUENCE OF 1-30, FUNCTION, AND SUBUNIT.
RC   TISSUE=Venom;
RX   PubMed=9163349; DOI=10.1042/bj3230533;
RA   Polgar J., Magnenat E.M., Peitsch M.C., Wells T.N.C., Saqi M.S.A.,
RA   Clemetson K.J.;
RT   "Amino acid sequence of the alpha subunit and computer modelling of the
RT   alpha and beta subunits of echicetin from the venom of Echis carinatus
RT   (saw-scaled viper).";
RL   Biochem. J. 323:533-537(1997).
RN   [3]
RP   FUNCTION.
RC   TISSUE=Venom;
RX   PubMed=8481512;
RA   Peng M., Lu W., Beviglia L., Niewiarowski S., Kirby E.P.;
RT   "Echicetin: a snake venom protein that inhibits binding of von Willebrand
RT   factor and alboaggregins to platelet glycoprotein Ib.";
RL   Blood 81:2321-2328(1993).
RN   [4]
RP   FUNCTION, AND SUBUNIT.
RX   PubMed=11290595; DOI=10.1182/blood.v97.8.2333;
RA   Navdaev A., Dormann D., Clemetson J.M., Clemetson K.J.;
RT   "Echicetin, a GPIb-binding snake C-type lectin from Echis carinatus, also
RT   contains a binding site for IgMkappa responsible for platelet agglutination
RT   in plasma and inducing signal transduction.";
RL   Blood 97:2333-2341(2001).
CC   -!- FUNCTION: Echicetin itself inhibits aggregation of washed platelets
CC       induced by vWF, thrombin or alboaggregin-A (PubMed:8481512,
CC       PubMed:11290595). However, when complexed with the pentameric plasma
CC       immunoglobulin Mkappa (IgMkappa), echicetin binds specifically to GPIb
CC       and activates platelets. This is caused by P-selectin expression and
CC       activation of alpha-IIb/beta-3 as well as tyrosine phosphorylation of
CC       several signal transduction molecules, including p53/56(LYN), p64,
CC       p72(SYK), p70 to p90, and p120 (PubMed:11290595). In vivo, it induces
CC       thrombocytopenia when injected into mice (PubMed:8481512), probably
CC       accounting of activation of platelets rather than inhibition
CC       (PubMed:11290595). {ECO:0000269|PubMed:11290595,
CC       ECO:0000269|PubMed:8481512, ECO:0000269|PubMed:9163349}.
CC   -!- SUBUNIT: Heterodimer of subunits alpha and beta; disulfide-linked
CC       (PubMed:9163349). Forms an active complex with the pentameric
CC       immunoglobuline Mkappa (IgMkappa) (PubMed:11290595).
CC       {ECO:0000269|PubMed:11290595, ECO:0000269|PubMed:9163349}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:7999097}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland. {ECO:0000305}.
CC   -!- SIMILARITY: Belongs to the snaclec family. {ECO:0000305}.
CC   -!- CAUTION: The name echicetin has been given to 2 different proteins,
CC       this one from E.carinatus sochureki and another one for which the
CC       subspecies has not been specified (E.carinatus). Most experiments have
CC       been done on E.carinatus sochureki. {ECO:0000305}.
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DR   PIR; JC2415; JC2415.
DR   AlphaFoldDB; P81996; -.
DR   SMR; P81996; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   Gene3D; 3.10.100.10; -; 1.
DR   InterPro; IPR001304; C-type_lectin-like.
DR   InterPro; IPR016186; C-type_lectin-like/link_sf.
DR   InterPro; IPR018378; C-type_lectin_CS.
DR   InterPro; IPR016187; CTDL_fold.
DR   Pfam; PF00059; Lectin_C; 1.
DR   SMART; SM00034; CLECT; 1.
DR   SUPFAM; SSF56436; SSF56436; 1.
DR   PROSITE; PS00615; C_TYPE_LECTIN_1; 1.
DR   PROSITE; PS50041; C_TYPE_LECTIN_2; 1.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Disulfide bond; Hemostasis impairing toxin;
KW   Platelet aggregation inhibiting toxin; Secreted; Toxin.
FT   CHAIN           1..123
FT                   /note="Snaclec echicetin subunit beta"
FT                   /id="PRO_0000046702"
FT   DOMAIN          1..121
FT                   /note="C-type lectin"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00040"
FT   DISULFID        2..13
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00040"
FT   DISULFID        30..119
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00040"
FT   DISULFID        75
FT                   /note="Interchain (with C-81 in subunit alpha)"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00040"
FT   DISULFID        96..111
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00040"
SQ   SEQUENCE   123 AA;  14869 MW;  C42C0AD7CDE18CA6 CRC64;
     NCLPDWSVYE GYCYKVFKER MNWADAEKFC MKQVKDGHLV SFRNSKEVDF MISLAFPMLK
     MELVWIGLSD YWRDCYWEWS DGAQLDYKAW DNERHCFAAK TTDNQWMRRK CSGEFYFVCK
     CPA