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Disagregin, a 6kDa protein isolated from salivary glands of the tickOrnithodoros Moubata,is a potent and selective inhibitor of fibrinogen dependent platelet aggregation and of the adhesion of platelets to fibrinogen (Karczewskiet al.(1994)J. Biol. Chem.269, 6702–6708). In the current study the interaction of disagregin with purified glycoprotein IIb-IIIa (GPIIb-IIIa) was examined. Biotin-labeled disagregin (b-disagregin) bound to GPIIb-IIIa immobilized on the surface of the ELISA plate. This binding was specific, dependent on divalent cations, and was blocked by the peptides fibrinogen γ-chain fgγ(400-411), GPIIb(296-306) and by the RGD-containing peptide, GRGDSP. Disagregin also bound to soluble GPIIb-IIIa as demonstrated in studies using the chemical crosslinker, BS3. This binding was inhibited by the peptides fgγ(400-411) and GPIIb(296-306). In contrast to the results in the solid phase, peptide GRGDSP had no effect on the binding of b-disagregin to soluble GPIIb-IIIa. These data demonstrate that disagregin binds to GPIIb-IIIa through a mechanism distinct from that used by RGD-containing disintegrins. Further analysis of the region(s) of disagregin which bind to GPIIb-IIIa should provide useful information for molecular modeling of the fibrinogen binding site on GPIIb-IIIa and for the design of a new class of potent fibrinogen receptor antagonists.

The relationship between the arrangement of cell events occurring in cambium in a definite configuration and the grain pattern of wood was investigated. Taking into consideration the growth activity of fusiform cell ends, a model of a migrating morphogenetic wave determining an event configuration was made. Waves of length ?=1 m for the periods T=2 years and T=3 years and waves of lengths ?=l m and ?=0.04 m for the period T=10 years were considered. On the model, events from successive annual rings, conventionally comprising 10 cell layers each, were summed. In this way, event maps were obtained. For wave ?=4 mm, the domain pattern on the modelled map was compatible with the grain pattern. The domain pattern for the wave ?=1 m was impossible to recreate because the wave “migrated too fast”. In this case, the pattern of event configuration, incompatible with the grain pattern, formed microareas, which were not domains.

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