S100 protein-annexin interactions: a model of the (Anx2-p11)(2) heterotetramer complex

The (Anx2)(2)(p11)(2) heterotetramer has been implicated in endo- and exocy tosis in vivo and in liposome aggregation in vitro. Here we report on the m odelling of the heterotetramer complex using docking algorithms. Two types of models are generated-heterotetramer and heterooctamer. On the basis of t he agreement between the calculated (X-ray) electron density and the observ ed projected density from cryo-electron micrographs on the one hand, and ca lculated energy criteria on the other hand, the heterotetramer models are p roposed as the most probable, and one of them is selected as the best model . Analysis of this model at an atomic level suggests that the interaction b etween the Anx2 core and p11 has an electrostatic character, being stabilis ed primarily through charged residues. (C) 2000 Elsevier Science B.V. All r ights reserved.