Two forms of the gamma subunit of G protein were purified from bovine lung, and were identified as gamma10 and gamma11 by analyses of partial amino acid sequences and reactivity with specific antibodies. The N-terminal amino acid residue of gamma11 was an unmodified Pro2, and the purified gamma11 was freed from beta even under non-denaturing conditions. Western blots with specific antibodies against gamma10 and gamma11 showed that both gamma subunits are present in a variety of tissues in the rat, with a particular abundance of gamma11 in the platelets.