# INTERACTIONS OF THE LUTROPIN RECEPTOR

> **NIH NIH R01** · UNIVERSITY OF WYOMING · 1994 · $205,331

## Abstract

The LH receptor (LH-R) is a member of the G-protein-coupled receptor
family and comprises an extracellular N-terminal half and a membrane-
associated C-terminal half of a similar size The long-term goal of this
project is to define the structural basis of hormone-dependent LH
receptor-modulation and subsequent G-protein-activation. Hormonal
responses are observed only after the hormone interacts with the
receptor. Understanding how the receptor-modulation induces signal
transduction necessitates the elucidation of hormone-receptor
interactions and the determination of contact sites between the hormone
and the receptor. The immediate objective is to determine these contact
sites and to understand hCG-receptor interactions.

The results of our studies suggest the presence of one or more hormone-
receptor contact sites in each of hCGalpha, hCGbeta, the N-terminal half
of LH-R and the C-terminal half of LH-R. In the HCGALPHA subunit, the C-
terminal 4AAs (-Tyr-His-Lys-Ser) are essential for receptor-binding.
AlphaPeptide (-Tyr-His-Lys-Ser) binds to the C-terminal half and
stimulates CAMP synthesis and, particularly, AlphaLys91 is important for
CAMP inducibility. This 4 amino acid peptide appears to have two sites,
one for a receptor-contacting and the other for stimulation  of CAMP
synthesis. These and other contacts sites between HCG and LH-R will be
determined in this study.

To facilitate this study, we have prepared the wild type and various
hCGs, LH-Rs, the C-terminal half of LH-R and the N-terminal half of LH-R
(some naturally occurring soluble receptors). These hormones and
receptors are expressed in stably transfected cell lines. For large
quantity preparations, these CDNAS have been constructed in Vaculovirus
and will be expressed in new more efficient SF21 cells. In addition, a
number of HCG alpha peptides and LH-R peptides are available and
antibodies against these peptides are being prepared. By using hormone
binding and CAMP assays as well as affinity-labeling, we are at a
breakthrough point to determine hormone-receptor contact sites and to
identify specific amino acid residues in these sites. In addition, we
hope to define the relationship of the high affinity HCG site in the N-
terminal half and the low affinity HCG site in the C-terminal half of
LH-R as well as the molecular mechanisms of HCG-dependent receptor-
modulation to activate G-proteins. These results will serve as a model
for not only other glycoproteins and their receptors but also bioactive
peptides such as substance P and their receptors.

## Key facts

- **NIH application ID:** 2197717
- **Project number:** 5R01HD018702-18
- **Recipient organization:** UNIVERSITY OF WYOMING
- **SAM.gov UEI:** FDR5YF2K32X5
- **Principal Investigator:** Tae H. Ji
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1994
- **Award amount:** $205,331
- **Award type:** 5
- **Project period:** 1992-02-01 → 1996-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/2197717

## Citation

> US National Institutes of Health, RePORTER application 2197717, INTERACTIONS OF THE LUTROPIN RECEPTOR (5R01HD018702-18). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/2197717. Licensed CC0.

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