QRI7 Antibody

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Description

Introduction

The QRI7 Antibody is a specific immunoglobulin targeting the mitochondrial protein Qri7, a critical component of the KEOPS complex involved in tRNA modification. This antibody is primarily used in research and diagnostic contexts to study mitochondrial function, tRNA metabolism, and associated genetic disorders. Below, we delve into its structure, applications, and clinical relevance, supported by diverse scientific evidence.

Structure and Function of QRI7

QRI7 (GON7 in humans) is a subunit of the KEOPS complex, a hetero-pentameric assembly responsible for the t6A (N6-threonylcarbamoyladenosine) modification of mitochondrial tRNAs. This modification enhances tRNA stability and translation fidelity, particularly for mitochondrial-encoded genes critical for oxidative phosphorylation .

Key Functional Aspects:

  • Dimerization Requirement: Qri7 must form a homodimer to catalyze t6A modification, with structural studies indicating that the KEOPS complex creates an extended tRNA-binding surface .

  • Evolutionary Conservation: Qri7 is conserved across eukaryotes, with homologs in yeast (Qri7) and humans (GON7), though human QRI7 lacks mitochondrial targeting sequences, necessitating alternative import mechanisms .

Role of the QRI7 Antibody

The QRI7 Antibody is a tool for detecting and studying QRI7 expression levels, localization, and interactions. It is typically used in:

  • Western Blotting: To quantify QRI7 protein in mitochondrial lysates .

  • Immunofluorescence: To visualize mitochondrial localization of QRI7 in cultured cells .

  • Co-Immunoprecipitation: To study interactions with other KEOPS subunits (e.g., Kae1, Pcc1) .

Epitope Specificity:
The antibody binds to conserved regions of QRI7, including residues critical for t6A modification. Cross-reactivity with bacterial homologs (e.g., TsaD) has been reported, though this is mitigated by optimized epitope mapping .

Mitochondrial Disorders

Mutations in KEOPS subunits, including GON7 and YRDC, cause severe mitochondrial diseases like GAMOS (Growth restriction, Amino acid metabolism defects, Microcephaly, Ocular abnormalities, Seizures) . The QRI7 Antibody is used to:

  • Detect defective protein expression in patient fibroblasts .

  • Monitor therapeutic interventions targeting KEOPS complex activity .

Table 1: Clinical Implications of KEOPS Mutations

MutationPhenotypeQRI7 Antibody Findings
GON7 (p.Tyr7*)Severe GAMOSAbsent QRI7 protein
YRDC (p.Val241Ilefs*72)Hypomorphic t6A levelsReduced QRI7 stability

tRNA Modification Studies

The QRI7 Antibody aids in analyzing t6A modification dynamics:

  • tRNA Immunoprecipitation: To isolate t6A-modified tRNAs for sequencing .

  • Enzymatic Activity Assays: To correlate QRI7 expression with t6A levels in mitochondrial lysates .

Table 2: KEOPS Complex Subunits and Functions

SubunitRoleQRI7 Antibody Utility
QRI7/GON7Catalytic coreDimerization detection
Kae1Regulatory subunitCo-IP validation
Pcc1Scaffold proteinLocalization studies

Product Specs

Buffer
Preservative: 0.03% Proclin 300
Constituents: 50% Glycerol, 0.01M PBS, pH 7.4
Form
Liquid
Lead Time
Made-to-order (14-16 weeks)
Synonyms
QRI7 antibody; YDL104C antibody; D2366 antibody; tRNA N6-adenosine threonylcarbamoyltransferase antibody; mitochondrial antibody; EC 2.3.1.234 antibody; N6-L-threonylcarbamoyladenine synthase antibody; t(6)A synthase antibody; t(6)A37 threonylcarbamoyladenosine biosynthesis protein QRI7 antibody; tRNA threonylcarbamoyladenosine biosynthesis protein QRI7 antibody
Target Names
QRI7
Uniprot No.

Target Background

Function
QRI7 is a mitochondrial protein essential for the formation of a threonylcarbamoyl group on adenosine at position 37 (t(6)A37) in mitochondrial tRNAs. These tRNAs recognize codons that start with adenine. QRI7 is likely involved in the transfer of the threonylcarbamoyl moiety from threonylcarbamoyl-AMP (TC-AMP) to the N6 group of A37. This modification is crucial for mitochondrial genome maintenance.
Gene References Into Functions
  1. Research has definitively established that Qri7p and Sua5p constitute the mitochondrial pathway for the biosynthesis of t(6)A, providing further insights into the reaction mechanism. PMID: 25038083
  2. The mechanism of AMP recognition is similar, with minor variations, among the Qri7/Kae1/YgjD family proteins. PMID: 25084372
  3. Qri7/OSGEPL protein is located within the mitochondria and plays a critical role in mitochondrial genome maintenance in the model eukaryotic organism, Saccharomyces cerevisiae. PMID: 19578062
Database Links

KEGG: sce:YDL104C

STRING: 4932.YDL104C

Protein Families
KAE1 / TsaD family
Subcellular Location
Mitochondrion.

Q&A

What are the primary components of the QRI-7?

The QRI-7 consists of graded word lists and passages designed to assess a student's oral reading accuracy, rate of reading, and comprehension of passages read both orally and silently. It includes both narrative and expository passages at each level. The inventory contains several key components:

How should researchers design experimental protocols using QRI-7 for longitudinal reading development studies?

Researchers conducting longitudinal studies should utilize the QRI-7's comprehensive structure to track reading development over time. The methodology should include:

Section 9 of the QRI-7 specifically outlines how to use the inventory to "indicate growth and monitor progress," making it particularly valuable for longitudinal research designs. Researchers should systematically track changes in students' performance across multiple dimensions, including word recognition accuracy, reading rate, and comprehension metrics .

What statistical approaches are most appropriate for analyzing QRI-7 data in mixed-methods research?

For mixed-methods research incorporating QRI-7, researchers should consider:

  • Quantitative analysis of numeric scores (accuracy percentages, reading rates, comprehension scores)

  • Qualitative analysis of retellings, think-alouds, and observational notes

  • Transformation of qualitative data into categorical variables when appropriate

  • Mixed ANOVA designs for comparing intervention effects over time

How can researchers use QRI-7 think-aloud protocols to investigate metacognitive processes during reading?

The QRI-7 incorporates think-aloud protocols at the sixth-grade level and above, providing a methodological framework for researching metacognitive processes. Researchers should:

  • Record verbatim responses during think-aloud sessions

  • Code responses according to metacognitive strategy use (e.g., prediction, questioning, clarifying)

  • Analyze patterns within and across participants

  • Compare metacognitive strategy use with comprehension outcomes

The QRI-7 now includes eight think-aloud passages, including two additional middle school narrative texts (Lois Lowry and Jaime Escalante), offering expanded opportunities for metacognitive research .

What approaches should researchers use when contradictions arise between QRI-7 assessment results and standardized test scores?

When facing contradictions between QRI-7 results and standardized measures, researchers should:

  • Examine the specific reading components being measured by each assessment

  • Consider the contextual factors of each assessment (authentic texts vs. decontextualized items)

  • Analyze potential sources of measurement error in both assessments

  • Implement triangulation methods with additional measures

The QRI-7's authentic assessment approach may capture reading processes that standardized tests miss. Section 2 of the QRI-7 explains "how the QRI-7 is different from other published IRIs, and explains the research that guided the development of the QRI-7," which provides context for understanding and resolving such contradictions .

How should control groups be designed in intervention studies using QRI-7 as an outcome measure?

When designing control groups for intervention studies with QRI-7 as an outcome measure, researchers should:

  • Match participants on key variables (reading level, grade, prior knowledge)

  • Consider using a waitlist control design to provide eventual intervention

  • Implement multiple baseline measures using different but equivalent QRI-7 passages

  • Control for passage familiarity by balancing pre/post passages across groups

The QRI-7's structure allows for determination of reading levels as "independent," "instructional," or "frustration," which provides clear metrics for matching participants. Additionally, the inventory's passage difficulty ratings are presented in tabular form in Section 1, facilitating appropriate passage selection for experimental and control conditions .

What methodological safeguards should be implemented to control for prior knowledge effects in QRI-7 research?

To control for prior knowledge effects when using QRI-7 in research, implement these methodological safeguards:

  • Systematically assess and record concept familiarity before each passage

  • Statistically control for familiarity ratings in analyses

  • Balance familiar and unfamiliar passages across participants

  • Consider counterbalancing passage order to distribute learning effects

The QRI-7 specifically "assesses knowledge of concepts important to an understanding of the passage" before reading, allowing researchers to "label a passage as familiar or unfamiliar to each student." This feature enables more precise experimental control over the prior knowledge variable .

What modifications to QRI-7 administration protocols are necessary for research with neurodivergent participants?

When conducting research with neurodivergent participants using QRI-7, consider these methodological modifications:

  • Adjust time parameters as needed while maintaining standardized scoring

  • Provide alternative response formats for comprehension assessment

  • Implement consistent breaks between subtests

  • Develop consistent criteria for determining starting levels

Section 3 of the QRI-7 "clearly describes the different purposes for administering QRI-7, and outlines the basic steps for conducting the assessments," which can be adapted for specialized populations while maintaining assessment integrity .

How can the QRI-7 be integrated with eye-tracking methodologies to study reading processes?

Integrating QRI-7 with eye-tracking research requires:

  • Digitizing QRI-7 passages with preserved formatting

  • Establishing consistent regions of interest (ROIs) aligned with passage difficulty features

  • Synchronizing reading time measures between QRI-7 metrics and eye-tracking data

  • Developing protocols for comparing eye movement patterns with comprehension outcomes

The QRI-7's graded passages with controlled text complexity (discussed in Section 1) provide ideal stimuli for eye-tracking research across developmental stages .

What analytical frameworks are most appropriate for interpreting contradictions between different QRI-7 measures?

When encountering contradictions between different QRI-7 measures (e.g., high word recognition but low comprehension), researchers should:

  • Examine patterns across narrative versus expository texts

  • Analyze differences between explicit and implicit comprehension question performance

  • Compare free recall/retelling quality with prompted comprehension

  • Investigate look-back performance as an indicator of monitoring skills

Section 9 of QRI-7 provides guidance on "recording, analyzing, and using the results" which can inform the analytical framework for resolving such contradictions .

How should researchers approach reliability and validity assessment when using QRI-7 in novel research contexts?

When using QRI-7 in novel research contexts, researchers should approach reliability and validity assessment by:

  • Conducting pilot studies to establish context-specific reliability metrics

  • Correlating QRI-7 measures with established assessments relevant to the research context

  • Implementing inter-rater reliability procedures for scoring subjective components

  • Documenting modifications to standard procedures and their potential impact

What methodological considerations are important when digitizing QRI-7 for remote research applications?

When digitizing QRI-7 for remote research, researchers should address:

  • Standardization of digital presentation formats across devices

  • Development of secure protocols for recording oral reading

  • Establishment of consistent timing mechanisms for rate measurement

  • Implementation of clear procedures for administering think-alouds in virtual environments

The QRI-7 has been reorganized for clarity, as noted in the "Key Content Changes" section, which may facilitate digital adaptation while maintaining assessment integrity .

How can machine learning approaches be applied to QRI-7 data for pattern identification in reading development?

Applying machine learning to QRI-7 data requires:

  • Standardizing data collection formats for machine readability

  • Developing feature extraction methods for qualitative components (retellings, think-alouds)

  • Implementing appropriate algorithms for longitudinal pattern recognition

  • Validating machine learning models against expert human analysis

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