The invention provides nanosensors and
nanosensor components for the detection of
ion channel activity,
receptor activity, or
protein protein interactions. Certain of the
nanosensor components comprise a
nanoparticle and recognition domain. Following contact with cells and, optionally,
internalization of the
nanosensor component by a
cell, the recognition domain binds to a target domain, e.g., a
heterologous target domain, of a polypeptide of interest such as an
ion channel
subunit,
G protein coupled
receptor (GPCR), or
G protein subunit.
Ion channel activity, GPCR activity, or altered
protein interaction results in a detectable
signal. The nanoparticles may be functionalized so that they respond to the presence of an
ion by altering their proximity. Certain of the nanosensors utilize the phenomenon of
plasmon resonance to produce a
signal while others utilize magnetic properties, RET, and / or ion-sensitive moieties. Also provided are polypeptides, e.g.,
ion channel subunits, comprising a
heterologous target domain, and
cell lines that express the polypeptides. Further provided are a variety of methods for detecting
ion channel activity,
receptor activity, or protein interaction and for identifying compounds that modulate one or more of these. In certain embodiments the invention allows the user to detect the activity of specific ion channels even in the presence of other channels that permit passage of the same ion(s) or result in activation of the same downstream targets, thereby achieving improved specificity in high
throughput screens while at the same time providing a high
signal to
noise ratio.