Homo- and heteromeric assembly of TRPV channel subunits

Abstract

The vanilloid receptor-related TRP channels (TRPV1-6) mediate thermosensation, pain perception and epithelial Ca2+ entry. As the specificity of TRPV channel heteromerization and determinants governing the assembly of TRPV subunits were largely elusive, we investigated the TRPV homo- and heteromultimerization. To analyze the assembly of TRPV subunits in living cells, we generated fluorescent fusion proteins or FLAG-tagged TRPV channel subunits. The interaction between TRPV subunits was assessed by analysis of the subcellular colocalization, fluorescence resonance energy transfer and coimmunoprecipitation. Our results demonstrate that TRPV channel subunits do not combine arbitrarily. With the exception of TRPV5 and TRPV6, TRPV channel subunits preferentially assemble into homomeric complexes. Truncation of TRPV1, expression of cytosolic termini of TRPV1 or TRPV4 and construction of chimeric TRPV channel subunits revealed that the specificity and the affinity of the subunit interaction is synergistically provided by interaction modules located in the transmembrane domains and in the cytosolic termini. The relative contribution of intramolecularly linked interaction modules presumably controls the overall affinity and the specificity of TRPV channel assembly.

Emerging roles of TRPM6/TRPM7 channel kinase signal transduction complexes

“…There is evidence that within the TRPV subfamily, heteromeric interactions are only detectable between TRPV1 and TRPV2, and between TRPV5 and TRPV6 subunits, while TRPV3 and TRPV4 assembly is restricted to homooligomeric complexes Hellwig et al 2005).…”

“…The third and fourth ankyrin repeats positioned in Nterminus of TRPV6 (Erler et al 2004) 3. The N-and C-termini for TRPV5 and TRPV4 complexes Hellwig et al 2005) 4. The transmembrane segments for TRPV1 subunits (Hellwig et al 2005) At present, a unifying structural principle underlying TRP channel multimerization still remains elusive.…”

“…The N-and C-termini for TRPV5 and TRPV4 complexes Hellwig et al 2005) 4. The transmembrane segments for TRPV1 subunits (Hellwig et al 2005) At present, a unifying structural principle underlying TRP channel multimerization still remains elusive. The physiological relevance of heteromultimerization among TRP proteins is only incompletely understood.…”

Luminal Chloride-dependent Activation of Endosome Calcium Channels

“…Various reports suggest that the EE itself function as the Ca 2ϩ source (10 -12). Although Ca 2ϩ release through ion channels in EE has not been shown, the presence of TRPV2 protein in EE (1) and in intracellular vesicles (13,14) suggests that the ECC could be a TRP-like channel.…”

“…ECC was inhibited by ϳ500 M to 1 mM La 3ϩ , RuR, and amiloride (as are other TRP channels) and was potentiated by acidic pH, 100 M La 3ϩ , and 200 M 2-APB. TRPV2 was shown to form a heteromultimer with TRPV1 and/or TRPV3 (14). All three TRPV1-3 are potentiated by 2-APB (24).…”