The MAM (Meprin/A5-protein/PTPmu) Domain Is a Homophilic Binding Site Promoting the Lateral Dimerization of Receptor-like Protein-tyrosine Phosphatase µ

The MAM (meprin/A5-protein/PTPmu) domain is present in numerous proteins with diverse functions. PTPmu belongs to the MAM-containing subclass of protein-tyrosine phosphatases (PTP) able to promote cell-to-cell adhesion. Here we provide experimental evidence that the MAM domain is a homophilic binding site of PTPmu. We demonstrate that the MAM domain forms oligomers in solution and binds to the PTPmu ectodomain at the cell surface. The presence of two disulfide bridges in the MAM molecule was evidenced and their integrity was found to be essential for MAM homophilic interaction. Our data also indicate that PTPmu ectodomain forms oligomers and mediates the cellular adhesion, even in the absence of MAM domain homophilic binding. Reciprocally, MAM is able to interact homophilically in the absence of ectodomain trans binding. The MAM domain therefore contains independent cis and trans interaction sites and we predict that its main role is to promote lateral dimerization of PTPmu at the cell surface. This finding contributes to the understanding of the signal transduction mechanism in MAM-containing PTPs

Functional, fractal nonlinear response with application to rate processes with memory, allometry, and population genetics

We give a functional generalization of fractal scaling laws applied to response problems as well as to probability distributions. We consider excitations and responses, which are functions of a given state vector. Based on scaling arguments, we derive a general nonlinear response functional scaling law, which expresses the logarithm of a response at a given state as a superposition of the values of the logarithms of the excitations at different states. Such a functional response law may result from the balance of different growth processes, characterized by variable growth rates, and it is the first order approximation of a perturbation expansion similar to the phase expansion. Our response law is a generalization of the static fractal scaling law and can be applied to the study of various problems from physics, chemistry, and biology. We consider some applications to heterogeneous and disordered kinetics, organ growth (allometry), and population genetics. Kinetics on inhomogeneous reconstructing surfaces leads to rate equations described by our nonlinear scaling law. For systems with dynamic disorder with random energy barriers, the probability density functional of the rate coefficient is also given by our scaling law. The relative growth rates of different biological organs (allometry) can be described by a similar approach. Our scaling law also emerges by studying the variation of macroscopic phenotypic variables in terms of genotypic growth rates. We study the implications of the causality principle for our theory and derive a set of generalized Kramers–Kronig relationships for the fractal scaling exponents

A re-evaluation of the kinetic equations for hyperbolic tight-binding inhibition.

(c) 2006 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.Proceedings of the 2006 IEEE/RSJ International Conference on Intelligent Robots and Systems October 9 - 15, 2006, Beijing, ChinaDigital Object Identifier : 10.1109/IROS.2006.282127A teleoperation system for controlling a robot with fast dynamics over the Internet has been constructed. It employs a predictive control structure with an accurate dynamic model of the robot to overcome problems caused by varying delays. The operator interface uses a stereo virtual reality display of the robot cell, and a haptic device for force feed-back including virtual obstacle avoidance forces