Provided is an emissions treatment system for an exhaust stream, having a NOx storage reduction (NSR) catalyst with a NOx sorbent at a concentration of at least 0.1 g/in3 and a platinum group metal component dispersed on a refractory metal oxide support; and, an SCR catalyst disposed downstream of the NSR catalyst. The emissions treatment system is advantageously used for the treatment of exhaust streams from diesel engines and lean burn gasoline engines.