title: Introduction to the concept of functioning-dependent structures in living cells.
abstract: The assembly of proteins into larger structures may confer advantages such as increased resistance to hydrolytic enzymes. metabolite channelling, and reduction of the number of proteins or other active molecules required for cell functioning. We propose the term functioning-dependent structures (FDSs) for those associations of proteins that are created and maintained by their action in accomplishing a function, as reported in many experiments. Here we model the simplest possible cases of two-partner FDSs in which the associations either catalyse or inhibit reactions. We show that FDSs may display regulatory properties (e.g., a sigmoidal response or a linear kinetic behaviour over a large range of substrate concentrations) even when the individual proteins are enzymes of the Michaelis-Menten type. The possible involvement of more complicated FDSs or of FDS networks in real living systems is discussed. From the thermodynamic point of view, FDS formation and decay are responsible for an extra production of entropy, which may be considered characteristic of living systems.
authors.affiliation: Laborartoire AMMIS, FRE CNRS 2829, Faculté des Sciences, Université de Rouen, 76821 Mont-Saint-Aignan, France. michel.thellier@univ-rouen.fr
authors.forename: Michel
authors.initials: M
authors.lastname: Thellier
authors.forename: Guillaume
authors.initials: G
authors.lastname: Legent
authors.forename: Vic
authors.initials: V
authors.lastname: Norris
authors.forename: Christophe
authors.initials: C
authors.lastname: Baron
authors.forename: Camille
authors.initials: C
authors.lastname: Ripoll
mesh_terms: D002468:Cell Physiological Phenomena; D006867:Hydrolases / Q000378:metabolism; D007700:Kinetics; D008433:Mathematics; D008954:Models, Biological; D011506:Proteins / Q000378:metabolism
chemical_list: D011506:Proteins; D006867:Hydrolases