# Structural and biochemical studies of receptor tyrosine kinases

> **NIH VA I01** · NORTHPORT VA MEDICAL CENTER · 2024 · —

## Abstract

Receptor tyrosine kinases (RTKs) are essential components of signal transduction pathways that mediate cell-
to-cell communication. RTKs are normally under tight regulatory control and have low basal (non-ligand bound)
activity; they are activated transiently in response to specific stimuli. Insulin and insulin-like growth factor-1
(IGF1) are closely related polypeptide hormones/growth factors that regulate cell growth and metabolism.
Insulin and IGF1 exert their biological effects on target cells by binding to distinct cell surface receptors, the
insulin receptor (IR) and the IGF1 receptor (IGF1R), respectively, which are structurally related RTKs. Despite
extensive structural and biochemical studies of the separate ectodomains and cytoplasmic domains of these
receptors, a comprehensive understanding of the signal transduction mechanism for IR and IGF1R is still
lacking. To address these issues, we have produced highly purified preparations of full-length IR and IGF1R
that are detergent-soluble, functional, and responsive to their ligands. By complexing the receptors with known
downstream signaling proteins such as tyrosine phosphatase PTP1B and adapter protein IRS1, we will
determine by single-particle cryo-electron microscopy the configurations of the kinase domains and
downstream proteins as well as the specificity factors governing recruitment of these proteins to the activated
receptors. We will carry out functional mutagenesis experiments in mammalian cells to confirm structural
results, and to probe for sites of allosteric regulation. We will test IGF1R mutations recently found to be
associated with type 2 diabetes. Using a computational method (virtual ligand screening), we will identify novel
small molecule IR activators. We will also test the hypothesis that cellular sterol and lipid composition affects
transmembrane signaling by IR and IGF1R. To do this, we will take advantage of new methodology to
manipulate the composition of the plasma membrane in living cells. In our preliminary work, we have used this
approach to demonstrate the importance of membrane sterols on IR and IGF1R signaling. Our work supports
the hypothesis that IR localizes in liquid-ordered ("raft") domains when active. We will test this hypothesis via
deletion or insertion of hydrophobic residues. We will examine the possibility that statins alter the plasma
membrane environment and lead to decreased IR function. We will also reconstitute IR into lipid vesicles with
and without raft domains, and use fluorescence resonance energy transfer (FRET) to determine whether IR
moves to rafts upon insulin stimulation. The work proposed in this grant application will advance our knowledge
of the molecular mechanisms involved in transmembrane signaling by IR and IGF1R. This information should
prove to be valuable in the design of small-molecule agonists or inhibitors to modulate the function of these
RTKs.

## Key facts

- **NIH application ID:** 10790157
- **Project number:** 1I01BX006248-01A1
- **Recipient organization:** NORTHPORT VA MEDICAL CENTER
- **Principal Investigator:** W Todd MILLER
- **Activity code:** I01 (R01, R21, SBIR, etc.)
- **Funding institute:** VA
- **Fiscal year:** 2024
- **Award amount:** —
- **Award type:** 1
- **Project period:** 2023-10-01 → 2027-09-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10790157

## Citation

> US National Institutes of Health, RePORTER application 10790157, Structural and biochemical studies of receptor tyrosine kinases (1I01BX006248-01A1). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10790157. Licensed CC0.

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