ID   VM23B_ECHCA             Reviewed;          67 AA.
AC   P81631;
DT   15-JUL-1999, integrated into UniProtKB/Swiss-Prot.
DT   15-JUL-1999, sequence version 1.
DT   25-MAY-2022, entry version 69.
DE   RecName: Full=Disintegrin EC3B;
OS   Echis carinatus (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=40353;
RN   [1]
RP   PROTEIN SEQUENCE, FUNCTION, AND SUBUNIT.
RC   TISSUE=Venom;
RX   PubMed=10212222; DOI=10.1074/jbc.274.18.12468;
RA   Marcinkiewicz C., Calvete J.J., Marcinkiewicz M.M., Raida M.,
RA   Vijay-Kumar S., Huang Z., Lobb R.R., Niewiarowski S.;
RT   "EC3, a novel heterodimeric disintegrin from Echis carinatus venom,
RT   inhibits alpha4 and alpha5 integrins in an RGD-independent manner.";
RL   J. Biol. Chem. 274:12468-12473(1999).
CC   -!- FUNCTION: Inhibits adhesion of cells expressing alpha-4/beta-1
CC       (ITGA4/ITGB1) and alpha-4/beta-7 (ITGA4/ITGB7) integrins to the natural
CC       ligands vascular cell adhesion molecule 1 (VCAM-1) and mucosal
CC       addressin cell adhesion molecule 1 (MADCAM-1). It is also a weaker
CC       inhibitor of alpha-5/beta-1 (ITGA5/ITGB1) and alpha-2b/beta-3
CC       (ITGA2B/ITGB3) integrins. The inhibitory activity of EC3 towards alpha-
CC       4 integrins is associated with the MLD sequence of EC3B subunit. The
CC       ability of EC3 to inhibit ITGA5/ITGB1 resides in both subunits A and B.
CC       {ECO:0000269|PubMed:10212222}.
CC   -!- SUBUNIT: Heterodimer with EC3A; disulfide-linked.
CC       {ECO:0000269|PubMed:10212222}.
CC   -!- SUBCELLULAR LOCATION: Secreted.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC   -!- MISCELLANEOUS: Does not inhibit alpha-V/beta-3 (ITGAV/ITGB3) integrin.
CC       {ECO:0000305|PubMed:10212222}.
CC   -!- MISCELLANEOUS: The disintegrin belongs to the dimeric disintegrin
CC       subfamily.
CC   -!- SIMILARITY: Belongs to the venom metalloproteinase (M12B) family. P-II
CC       subfamily. P-IIe sub-subfamily. {ECO:0000305}.
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DR   AlphaFoldDB; P81631; -.
DR   SMR; P81631; -.
DR   PRIDE; P81631; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   GO; GO:0007155; P:cell adhesion; IEA:UniProtKB-KW.
DR   Gene3D; 4.10.70.10; -; 1.
DR   InterPro; IPR018358; Disintegrin_CS.
DR   InterPro; IPR001762; Disintegrin_dom.
DR   InterPro; IPR036436; Disintegrin_dom_sf.
DR   Pfam; PF00200; Disintegrin; 1.
DR   PRINTS; PR00289; DISINTEGRIN.
DR   SMART; SM00050; DISIN; 1.
DR   SUPFAM; SSF57552; SSF57552; 1.
DR   PROSITE; PS00427; DISINTEGRIN_1; 1.
DR   PROSITE; PS50214; DISINTEGRIN_2; 1.
PE   1: Evidence at protein level;
KW   Cell adhesion; Cell adhesion impairing toxin; Direct protein sequencing;
KW   Disulfide bond; Secreted; Toxin.
FT   CHAIN           1..67
FT                   /note="Disintegrin EC3B"
FT                   /id="PRO_0000101799"
FT   DOMAIN          1..65
FT                   /note="Disintegrin"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00068"
FT   MOTIF           42..44
FT                   /note="Cell attachment site; atypical (MLD)"
FT   DISULFID        6..29
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00068"
FT   DISULFID        7
FT                   /note="Interchain (with C-12 in EC3A)"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00068"
FT   DISULFID        12
FT                   /note="Interchain (with C-7 in EC3A)"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00068"
FT   DISULFID        20..26
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00068"
FT   DISULFID        25..50
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00068"
FT   DISULFID        38..57
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00068"
FT   VARIANT         11
FT                   /note="K -> T"
FT   VARIANT         40
FT                   /note="R -> K"
FT   VARIANT         55
FT                   /note="T -> S"
SQ   SEQUENCE   67 AA;  7424 MW;  4BB6624FCAB7505E CRC64;
     NSVHPCCDPV KCEPREGEHC ISGPCCRNCK FLNAGTICKR AMLDGLNDYC TGISTDCPRN
     RYKGKED