# Non-classical roles for opsins in taste and smell

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA SANTA BARBARA · 2020 · $418,410

## Abstract

Abstract
The goal of the proposed project is to build on our recent discovery of non-classical roles for opsins in diverse
sensory contexts, and specifically to unravel their contributions to the senses of taste and smell. It turns out
that opsins, which have been studied for >100 years as light sensors, are expressed outside of the visual
system and function in a variety of sensory modalities. Rather than serving exclusively in photosensation, we
are finding that opsins are broadly required sensory receptors, potentially playing roles as far-ranging as TRP
channels. In mammals, opsins are expressed in a large variety of extra-retinal cell types and organs. However,
the extra-ocular roles of these opsins are essentially unexplored. We propose to bring to bear a wide
combination of tools available for use in Drosophila to elucidate extra-retinal roles for opsins. The project will
employ an extensive suite of in vivo approaches including electrophysiology and Ca2+ imaging, behavioral
assays, cell biology and state-of-the art molecular genetic approaches, to study unconventional roles we found
for opsins in gustation and olfaction. In addition to the six rhodopsins that are required in the visual system
(Rh1-Rh6), flies encode a seventh family member (Rh7). Aim 1 will clarify a light-independent role for Rh7 in
the response of gustatory receptor neurons (GRNs) to an aversive tastant. We will test the proposal that Rh7
couples to a signaling cascade that endows GRNs with high sensitivity to the aversive chemical. Aim 2 will
investigate a potential role for an opsin in olfaction. Conceptually similar to our recent discovery that opsins
expressed in thermosensory neurons allow flies to sense small increases in temperature in the comfortable
range, we propose to test that an opsin acts in olfactory receptor neurons to detect minute concentrations of an
aversive odorant through an amplification cascade. Aim 3 focuses on illuminating the potential roles of two
opsins in the discrimination of foods on the basis of texture. The physical features of food include the viscosity
of liquid foods, and the hardness of solid foods. However, the mechanisms underlying food texture sensation
are poorly understood. We will investigate the contributions of two opsins to sensing the physical properties of
foods. Temperature also influences food palatability. Aim 4 will address the concept that the temperature-
dependent change in appeal of sugar-containing foods requires a member of the opsin family. In summary, the
proposed project will deepen our understanding of light-independent roles of opsins in gustation and olfaction,
and shape the proposal that opsins are broad, polymodal sensors. In view of the wide extra-ocular expression
of mammalian opsins, we suggest that this project will provide the conceptual framework for exploring similar
roles for opsins in mammals. Finally, taste and smell are critical for insect disease vectors to identify and bite
human hosts, and ...

## Key facts

- **NIH application ID:** 9928043
- **Project number:** 5R01DC016278-04
- **Recipient organization:** UNIVERSITY OF CALIFORNIA SANTA BARBARA
- **Principal Investigator:** CRAIG MONTELL
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $418,410
- **Award type:** 5
- **Project period:** 2017-06-01 → 2022-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9928043

## Citation

> US National Institutes of Health, RePORTER application 9928043, Non-classical roles for opsins in taste and smell (5R01DC016278-04). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9928043. Licensed CC0.

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