Trafficking and assembly of the cold-sensitive TRPM8 channel.
TRPM (transient receptor potential melastatin-like) channels are distinct from many other members of the transient receptor potential family in regard to their overall size (>1000 amino acids), the lack of N-terminal ankyrin-like repeats, and hydrophobicity predictions that may allow for more than six transmembrane regions. Common to each TRPM member is a prominent C-terminal coiled coil region. Here we have shown that TRPM8 channels assemble as multimers using the putative coiled coil region within the intracellular C terminus and that this assembly can be disturbed by a single point mutation within the coiled coil region. This mutant neither gives rise to functional channels nor do its subunits interact or form protein complexes that correspond to a multimer. However, they are still transported to the plasma membrane. Furthermore, wild-type currents can be suppressed by expressing the membrane-attached C-terminal region of TRPM8. To separate assembly from trafficking, we investigated the maturation of TRPM8 protein by identifying and mutating the relevant N-linked glycosylation site and showing that glycosylation is neither essential for multimerization nor for transport to the plasma membrane per se but appears to facilitate efficient multimerization and transport.
Erler
Isabell
I
Department of Pharmacology and Toxicology, University of Saarland, Medical Campus, 66421 Homburg, Germany.
Al-Ansary
Dalia M M
DM
Wissenbach
Ulrich
U
Wagner
Thomas F J
TF
Flockerzi
Veit
V
Niemeyer
Barbara A
BA
D000818:Animals; D002460:Cell Line; D003080:Cold Temperature; D006801:Humans; D047468:Immunoprecipitation; D016296:Mutagenesis; D016297:Mutagenesis, Site-Directed; D021381:Protein Transport; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D050053:TRPM Cation Channels / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D011994:Recombinant Proteins; D050053:TRPM Cation Channels; C425966:TRPM8 protein, human