NS3 helicase from the hepatitis C virus can function as a monomer or oligomer depending on enzyme and substrate concentrations.
Jennings TA, Mackintosh SG, Harrison MK, Sikora D, Sikora B, Dave B, Tackett AJ, Cameron CE, Raney KD. NS3 helicase from the hepatitis C virus can function as a monomer or oligomer depending on enzyme and substrate concentrations. J Biol Chem. 2009 Feb 20; 284(8):4806-14.