Refining the structure of hPIRT, a modulator of TRP channels, via measurement of residual dipolar couplings in nuclear magnetic resonance spectroscopy
Transient receptor potential channels (TRP channels) are a family of ion channels that mediate a wide variety of sensations, including pain, temperature, and mechanosensation. Human phosphoinositide-interacting regulator of TRP (hPIRT) is a 15.5 kDa, relatively uncharacterized membrane protein that has been shown to modulate the activity of certain TRP channels and some other ion channels. hPIRT is also able to interact with phosphatidylinositol-4,5-bisphosphate (PI(4,5)P¬2), a phospholipid that modulates the activity of many important signaling proteins, including TRP channels. Some information is already known about the structure of hPIRT: it contains a relatively unstructured N-terminus, two transmembrane helices, and a juxtamembrane region at the C-terminus that plays a role in binding PI(4,5)P2 and TRPV1. However, more detailed structural data about this molecule would be very informative in understanding how these interactions occur. In order to accomplish this, this thesis investigates the measurement of residual dipolar couplings (RDCs) in nuclear magnetic resonance spectroscopy (NMR) to refine the structure of hPIRT. RDCs are a measurable effect in NMR experiments caused by partial alignment of molecules solubilized in a weakly anisotropic medium. The resulting data set can be used to calculate bond angles within the protein relative to the axis of the external magnetic field, which will assist efforts to further constrain the structure of hPIRT.