Dynamics of Cdc42 network embodies a Turing-type mechanism of yeast cell polarity.

Complex biochemical networks can be understood by identifying their principal regulatory motifs and mode of action. We model the early phase of budding yeast cellular polarization and show that the biochemical processes in the presumptive bud site comprise a Turing-type mechanism. The roles of the prototypical activator and substrate are played by GTPase Cdc42 in its active and inactive states, respectively.

Computational model explains high activity and rapid cycling of Rho GTPases within protein complexes.

Formation of multiprotein complexes on cellular membranes is critically dependent on the cyclic activation of small GTPases. FRAP-based analyses demonstrate that within protein complexes, some small GTPases cycle nearly three orders of magnitude faster than they would spontaneously cycle in vitro. At the same time, experiments report concomitant excess of the activated, GTP-bound form of GTPases over their inactive form.

Mathematical model of mitochondrial ionic homeostasis: three modes of Ca2+ transport.

Mitochondria play an important role in regulation of Ca2+ homeostasis in a cell. Here we present a mathematical model of mitochondrial ion transport and use this model to analyse different modes of Ca2+ uptake by mitochondria. The model includes transport of H+, Ca2+, K+, inorganic phosphate and oxidative substrates across the inner mitochondrial membrane harboring permeability transition pore (PTP).

Spatiotemporal dynamics of contact activation factors of blood coagulation.

A new in vitro model is proposed for studying the spatiotemporal distributions of activated clotting factors, in which clotting is activated in a thin layer of non-stirred plasma supplemented with a fluorogenic substrate and is monitored by fluorescence from its cleavage product. Analysis of the spatiotemporal dynamics of factor XIa and kallikrein in glass-activated human plasma provides evidence that both contact factors remain restricted to the glass surface and possibly a narrow boundary zone (<0.1 mm).