TRPN

TRPN is a member of the transient receptor potential channel family of ion channels, which is a diverse group of proteins thought to be involved in mechanoreception. The TRPN gene was given the name "no mechanoreceptor potential C" (nompC) when it was first discovered in fruit flies, hence the "N" in TRPN. Since its discovery in fruit flies, TRPN homologs have been discovered and characterized in worms,frogs, and zebrafish.

Not much is known at this time about the structure of TRPN. X-ray crystallography studies of channel segments cloned from fruit flies and zebrafish have led to the hypothesis that multiple ankyrin repeats at TRPN's N-terminus are involved in the gating of the channel pore. Crystallography studies of TRPY1, a yeast TRP homolog, have shown that aromatic residues conserved across TRP family members, including TRPN, in the sixth transmembrane domain are critical to the gating mechanism as well.

As a mechanoreceptor, TRPN responds to impinging mechanical forces. Studies in TRPN deficient adult fruit flies and larvae have shown that these null mutants have severe difficulty moving, which suggests a role for TRPN in proprioception. This hypothesis is further strengthened by immunostaining studies in fruit flies that have shown TRPN localization in the cilia of campaniform sensilla and chordotonal organs in Johnston's organ. Further immunostaining studies in fruit flies have identified, with higher resolution techniques, that TRPN is localized at the distal end of motile mechanosensory cilia in Johnston's organ. However, TRPN is not required for transduction of mechanical stimuli in larvae or adult flies, suggesting that the TRPV channels nanchung and inactive may also serve a mechanosensory function.

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