Rab6a-Based Prenylation Assay for REP1 Activity Screening

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Solution Overview

Problem

Current assays for determining the activity of Rab escort protein 1 (REP1) in the context of choroideremia treatment are not sensitive enough, particularly when using Rab27a as a prenylation substrate, which results in weak signals and low sensitivity, making them unsuitable for reliable screening of gene therapy vectors.

Innovation Solution

Using Rab6a as a substrate in a prenylation reaction with REP1 and Rab geranylgeranyltransferase, along with a lipid donor substrate, to detect the lipidated Rab6a product, which provides a more sensitive and reliable method for assessing REP1 activity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Rab27a is used as a prenymlation substrate in the assay, then the assay can be performed with existing protocols, but the signal strength is weak and sensitivity is low

Engineering Contradiction:
Improveassay reliabilityVSAvoidassay sensitivity
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent changes the substrate parameter from Rab27a to Rab6a, which fundamentally alters the assay characteristics. Rab6a produces stronger prenymlation signals and higher sensitivity while maintaining assay reliability, directly resolving the contradiction between reliability and sensitivity.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If Rab27a is used as a substrate, then the assay protocol is established, but the signal-to-noise ratio is low making it unsuitable for screening

Engineering Contradiction:
Improveassay protocol establishmentVSAvoidsignal-to-noise ratio
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

By changing the substrate from Rab27a to Rab6a, the patent achieves a significantly improved signal-to-noise ratio that enables reliable screening of gene therapy vectors, while the assay remains straightforward to perform.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If existing assay methods are used for REP1 activity determination, then the methodology is available, but the sensitivity is insufficient for quality control screening

Engineering Contradiction:
Improveassay availabilityVSAvoidassay sensitivity
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent modifies the existing assay by substituting Rab6a for Rab27a as the substrate, transforming it into a high-sensitivity tool suitable for quality control screening of gene therapy vectors while maintaining the overall assay framework.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach significantly increases the sensitivity and signal-to-noise ratio of the assay, allowing for accurate and reliable determination of REP1 activity, particularly for AAV gene therapy vectors, and is suitable for quality control analysis of gene therapy vectors.

Implementation Method 1

detecting the lipidated Rab6a product

Methodology Applied
Scientific EffectPrenylation: Chemical Bonding

Data Source

PatentEP3426795B1Prenylation assay
Publication Date: 2021.01.27 NIGHTSTARX LTD
  • EP3426795B1 patent drawingFigure 1A~1
  • EP3426795B1 patent drawingFigure 2A~2
  • EP3426795B1 patent drawingFigure 3A~3

AI summary

A method for determining the activity of Rab escort protein 1 (REP1) comprising the steps: (a) providing a sample comprising REP1; (b) contacting the sample of step (a) with Rab6a, Rab geranylgeranyltransferase (Rab GGTase) and a lipid donor substrate; and (c) detecting the lipidated Rab6a product.