Molecular cloning and characterization of a mitogen-activated protein kinase-associated intracellular chloride channel

ERK7, a member of the mitogen-activated protein kinase family, has a carbox yl-terminal tail that is required for ERK7 activation, cellular localizatio n, and its ability to inhibit DNA synthesis. To identify proteins that inte ract With ERK7, we utilized a yeast two-hybrid screen with the COOH-termina l tail of ERK7 as bait and isolated the cDNA for a novel protein termed CLI C3. The interaction between CLIC3 and ERK7 in mammalian cells was confirmed by co-immunoprecipitation. CLIC3 has significant homology to human intrace llular chloride channels 1 (NCC27/CLIC1) and 2 and bovine kidney chloride c hannel p64, Like NCC27/CLIC1, CLIC3 is predominantly localized in the nucle us and stimulates chloride conductance when expressed in cells, Taken toget her, these results suggest that CLIC3 is a new member of the human CLIC fam ily. The observed interaction between CLIC3 and ERK7 is the first demonstra tion of a stable complex between a protein that activates chloride ion tran sport and a member of the mitogen-activated protein kinase family of signal transducers. The specific association of CLIC3 with the COOH-terminal tail of ERK7 suggests that CLIC3 may play a role in the regulation of cell grow th.