The large family of mammalian TRP (transient receptor potential) ion channels encompasses diverse sensory functions. TRP proteins consist of six transmembrane domains, with a pore-loop motif between the fifth and sixth domains and cytosolic N- and C-termini. The intracellular strands not only interact with various proteins and lipids, but also include essential multimerization regions. This review summarizes the current knowledge of the intrinsic assembly domains that assure tetrameric TRP channel formation.