Complete 1H, 13C, and 15N assignments for backbone and side-chain atoms of the 145 residue GTPase activating domain of Gs are presented. The combination of gradient-enhanced versions of the HNCACB and CBCA(CO)NNH pulse sequences provided enough information to obtain sequential backbone assignments for residues 2-145 of the polypeptide, as well as assignments of asparagine and glutamine side-chain amides. HBHA(CO)NNH, HCCH-TOCSY, and 13C/15N NOESY-HSQC experiments yielded side-chain 1H and 13C assignments. Chemical shift data and 15N NOESY-HSQC experiments provided information on the secondary structure of the domain, which is similar to that observed in the cognate domain in transducin, a related G protein. The functionally essential C-terminal 15 residues are disordered in solution. These assignments provide a basis for determining the solution structure of the domain.