A seat for a tubular treating system includes a single piece body having a central portion, and a frustoconical surface extending longitudinally from the central portion in a first direction configured to radially expand slips urged thereagainst. The seat also includes a collar extending longitudinally from the central portion in a second direction configured to be radially expanded into sealing engagement with a structure in response to a frustoconical member urged thereagainst. A seal surface is sealably engagable with a plug run thereagainst, and the seal surface is longitudinally displaced from the collar in the first direction.