We have used a yeast two-hybrid system to show that human papillomavirus E7 proteins can form oligomeric complexes in vivo. The carboxyl-terminal cysteine-rich metal-binding domain is critical for this activity although amino-terminal sequences also contribute to oligomerization. Our experiments also reveal that E7 possesses an intrinsic transcription activation activity in yeast, which resides in the amino terminus of the protein. (C) 1995 Academic Press, Inc.