IAA15 Antibody

Introduction to IAA15 Antibody

The IAA15 antibody is a specialized immunological tool used to detect and study the INDOLE-3-ACETIC ACID INDUCIBLE 15 (IAA15) protein, a member of the Aux/IAA family of transcriptional repressors in plants. This antibody enables researchers to investigate IAA15’s stability, post-translational modifications, and interactions with other proteins critical for auxin signaling pathways. Key applications include Western blotting, immunoprecipitation, and chromatin immunoprecipitation (ChIP) assays to dissect IAA15’s role in plant development, particularly lateral root formation .

Protein Stability and Degradation Analysis

IAA15 antibodies have been instrumental in demonstrating the protein’s rapid turnover via the ubiquitin-proteasome pathway. Key experiments include:

• Western Blotting: Anti-Flag antibodies detected IAA15 protein levels in transgenic Arabidopsis lines expressing Flag-tagged IAA15. Wild-type (WT) IAA15 was unstable under normal conditions, while the gain-of-function mutant IAA15 P75S exhibited enhanced stability even without proteasome inhibitors .

• Ubiquitination Assays: Anti-ubiquitin antibodies confirmed reduced poly-ubiquitination of the IAA15 P75S mutant compared to WT, explaining its resistance to degradation .

Table 1: Stability of IAA15 WT vs. P75S Mutant

Interaction Studies with ARF Transcription Factors

IAA15 antibodies facilitated the discovery of IAA15’s interaction with AUXIN RESPONSE FACTORS (ARF7 and ARF19), which regulate lateral root development:

• Yeast Two-Hybrid Assays: Full-length IAA15 was shown to bind ARF7 and ARF19, forming repressor complexes that inhibit auxin-responsive gene expression .

• Chromatin Immunoprecipitation (ChIP): Anti-Flag antibodies enriched IAA15-bound DNA fragments from the promoters of LBD16 and LBD29, genes directly activated by ARF7/ARF19 .

Table 2: IAA15 Binding to LBD16 and LBD29 Promoters

Role in Lateral Root Development

IAA15 antibodies revealed its negative regulatory role in lateral root formation:

• Transcriptional Repression: IAA15 overexpression reduced LBD16 and LBD29 expression by 70–80% compared to WT plants, as quantified by RT-qPCR .

• Phenotypic Analysis: Transgenic lines with stabilized IAA15 P75S showed 50% fewer lateral roots than WT under identical growth conditions .

Phosphorylation by MAP Kinases

Recent studies using IAA15 antibodies identified phosphorylation sites (e.g., Ser-126) targeted by MPK3/MPK6, linking auxin signaling to stress responses:

• Phosphorylation Assays: Immunoprecipitated IAA15 from drought-stressed plants showed enhanced phosphorylation, correlating with reduced lateral root growth .

Western Blotting Protocol

1. Sample Preparation: Extract total protein from 10-day-old seedlings treated with 50 μM MG132 (proteasome inhibitor) .

2. Electrophoresis: Separate 50 μg protein via SDS-PAGE.

3. Antibody Incubation: Use anti-Flag (1:2,000 dilution) or anti-ubiquitin (1:1,000) antibodies for detection .

Immunoprecipitation for Ubiquitination Assays

1. Protein Extraction: Use 1 mg total protein from MG132-treated seedlings.

2. IP Procedure: Incubate with anti-Flag agarose beads for 4 hours at 4°C.

3. Detection: Probe immunoprecipitates with anti-ubiquitin antibodies .