Calmodulin and S100A1 interact with N-terminus of TRPM3 channel.

Blanka Holakovska, Lenka Grycova, Michaela Jirku, Miroslav Sulc, Ladislav Bumba, Jan Teisinger

, 2012 Mar 27 , ,

Transient receptor potential melastatin 3 ion channel (TRPM3) belongs to the TRP family of cation-permeable ion channels involved in many important biological functions such as pain transduction, thermosensation and mechanoregulation. The channel was reported to play an important role in Ca2+ homeostasis but its gating mechanisms, functions and regulation are still under research. Utilizing biophysical and biochemical methods we characterized two independent domains, A35-K124 and H291-G382 on the TRPM3 N-terminus, responsible for interactions with the Ca2+ binding proteins calmodulin (CaM) and S100A1. We identified several positively charged residues within these domains as having a crucial impact on CaM/S100A1 binding. The data also suggest that the interaction is calcium-dependent. We also performed competition assays, which suggested that CaM and S100A1 are able to compete for the same binding sites within the TRPM3 N-terminus. This is the first time that such an interaction has been shown for TRP family members.