Isolation and characterization of EMS16, a C-lectin type protein from Echis multisquamatus venom, a potent and selective inhibitor of the alpha2beta1 integrin.
We have isolated and characterized EMS16, a potent and selective inhibitor of the alpha2beta1 integrin, from Echis multisquamatus venom. It belongs to the family of C-lectin type of proteins (CLPs), and its amino acid sequence is homologous with other members of this protein family occurring in snake venoms. EMS16 (M(r) approximately 33K) is a heterodimer composed of two distinct subunits linked by S-S bonds. K562 cells transfected with alpha2 integrin selectively adhere to immobilized EMS16, but not to two other snake venom-derived CLPs, echicetin and alboaggregin B. EMS16 inhibits adhesion of alpha2beta1-expressing cells to immobilized collagen I at picomolar concentrations, and the platelet/collagen I interaction in solution at nanomolar concentrations. EMS16 inhibits binding of isolated, recombinant I domain of alpha2 integrin to collagen in an ELISA assay, but not the interaction of isolated I domain of alpha1 integrin with collagen IV. Studies with monoclonal antibodies suggested that EMS16 binds to the alpha2 subunit of the integrin. EMS16 inhibits collagen-induced platelet aggregation, but has no effect on aggregation induced by other agonists such as ADP, thromboxane analogue (U46619), TRAP, or convulxin. EMS16 also inhibits collagen-induced, but not convulxin-induced, platelet cytosolic Ca(2+) mobilization. In addition, EMS16 inhibits HUVEC migration in collagen I gel. In conclusion, we report a new, potent viper venom-derived inhibitor of alpha2beta1 integrin, which does not belong to the disintegrin family.
Marcinkiewicz
C
C
Sol Sherry Thrombosis Research Center, Department of Pharmacology, and Department of Physiology, Temple University, School of Medicine, 3400 North Broad Street, Philadelphia, Pennsylvania 19140, USA. cmarcink@nimbus.temple.edu
Lobb
R R
RR
Marcinkiewicz
M M
MM
Daniel
J L
JL
Smith
J B
JB
Dangelmaier
C
C
Weinreb
P H
PH
Beacham
D A
DA
Niewiarowski
S
S
D000595:Amino Acid Sequence; D020013:Calcium Signaling / Q000187:drug effects; D002448:Cell Adhesion / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D019281:Dimerization; D004220:Disulfides; D004730:Endothelium, Vascular / Q000187:drug effects; D006801:Humans; D016023:Integrins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D037102:Lectins / Q000145:classification / Q000494:pharmacology*; D037181:Lectins, C-Type; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000378:metabolism; D010974:Platelet Aggregation / Q000187:drug effects; D011485:Protein Binding; D038981:Receptors, Collagen; D020539:Sequence Analysis, Protein; D014757:Viper Venoms / Q000737:chemistry*
D004220:Disulfides; C412704:EMS16 lectin, Echis multisquamtus; D016023:Integrins; D037102:Lectins; D037181:Lectins, C-Type; D010446:Peptide Fragments; D038981:Receptors, Collagen; D014757:Viper Venoms