# Time resolved SAXS studies on the RP2/Arl3 complex pp.484-485

> **NIH NIH P41** · ILLINOIS INSTITUTE OF TECHNOLOGY · 2020 · $162,592

## Abstract

To understand how signaling proteins function, it is crucial to know the timeordered
sequence of events that lead to the signaling state. When the messenger is chemical, the time
required to diffuse to and bind in the active site of a signaling protein is typically far longer than the timescale
for protein conformational change [1]. For the structural determination of the kinetics of enzymatic reactions
we will focus on small GTPases and their co-enzymes. Small GTPases are molecular switches that cycle
between a GTP-bound active and a GDP-bound inactive form. The switch is catalyzed by Guanine nucleotide
Exchange Factors (GEFs) and GTPase-Activating Proteins (GAPs), the latter catalyze the hydrolysis of GTP
to GDP to deactivate the small GTPase. This system is of very high, general importance in cell biology with
particular impact on disease processes, especially cancer, but also several infectious diseases. For proof-ofprinciple,
we chose the Arl3-RP2 complex as GTPase-GAP pair [2]. The gene encoding for the GAP protein
RP2 (Retinitis pigmentosa 2) is highly mutated
in patients of X-linked Retinitis pigmentosa,
with mutational hotspots in residues catalyzing
the GAP reaction on Arl3. Retinitis pigmentosa
refers to a heterogeneous group of inherited
ocular diseases that result in a progressive
retinal degeneration affecting 1 in 3,000–5,000
people.

## Key facts

- **NIH application ID:** 9841416
- **Project number:** 5P41GM103622-24
- **Recipient organization:** ILLINOIS INSTITUTE OF TECHNOLOGY
- **Principal Investigator:** THOMAS C IRVING
- **Activity code:** P41 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $162,592
- **Award type:** 5
- **Project period:** — → 2021-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9841416

## Citation

> US National Institutes of Health, RePORTER application 9841416, Time resolved SAXS studies on the RP2/Arl3 complex pp.484-485 (5P41GM103622-24). Retrieved via AI Analytics 2026-05-28 from https://api.ai-analytics.org/grant/nih/9841416. Licensed CC0.

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