Besides their role in the generation of action potentials, voltage-gated potassium channels are implicated in cellular processes ranging from cell division to cell death. The K+ channel regulator protein (KCNRC), identified as a putative tumor suppressor, reduces K+ currents through human K' channels hKv1.1 and hKv1.4 expressed in Xenopus oocytes. Current attenuation requires the presence of the N-terminal T1 Domain and immunoprecipitation experiments Suggest association of KCNRG with the N-terminus of the channel. Our data indicates that KCNRG is an ER-associated protein, which we propose regulates Kv1 family channel proteins by retaining a fraction of channels in endomembranes. (C) 2009 Elsevier Inc. All rights reserved.