Localization of tyrosine kinase-coding region in v-abl oncogene by the expression of v-abl-encoded proteins in bacteria

A series of plasmids containing different segments of the v-abl oncogene have been constructed to express different portions of the v- abl protein in bacteria. The tyrosine kinase activity of these proteins was determined by an in vitro assay employing histones or angiotensin II as substrates for the v-abl-encoded tyrosine kinase. These experiments show that the 5'-1.2 kilobases of v-abl is necessary and sufficient to produce an active tyrosine kinase which is functional as a monomeric soluble protein. The kinase-coding region corresponds to the minimal region of v-abl required for the transformation of fibroblasts. The kinase-coding region also coincides with the conserved protein sequences which are found in other tyrosine kinases. A compact domain of the v-abl protein including this kinase-coding region can accumulate to high levels in bacteria. The C-terminal region of the v- abl protein is not needed for the kinase activity and is rapidly degraded in bacteria

Rattling and freezing in a 1-D transport model

We consider a heat conduction model introduced in \cite{Collet-Eckmann 2009}. This is an open system in which particles exchange momentum with a row of (fixed) scatterers. We assume simplified bath conditions throughout, and give a qualitative description of the dynamics extrapolating from the case of a single particle for which we have a fairly clear understanding. The main phenomenon discussed is {\it freezing}, or the slowing down of particles with time. As particle number is conserved, this means fewer collisions per unit time, and less contact with the baths; in other words, the conductor becomes less effective. Careful numerical documentation of freezing is provided, and a theoretical explanation is proposed. Freezing being an extremely slow process, however, the system behaves as though it is in a steady state for long durations. Quantities such as energy and fluxes are studied, and are found to have curious relationships with particle density