At3g56080 Antibody

Introduction to At3g56080 (QUA3) Antibody

The At3g56080 antibody is a polyclonal antibody raised against the QUA3 protein, a putative homogalacturonan methyltransferase in Arabidopsis. QUA3 is a type II integral membrane protein localized to the Golgi apparatus and plays a role in pectin modification, critical for plant cell wall integrity .

Antibody Generation and Validation

The QUA3 antibody was generated using a synthetic peptide (CEDPRRNSQLSREMNFYR) corresponding to the N-terminal region of the DUF248 domain (Fig. 1B) . Key validation steps include:

Table 1: Antibody Specificity Validation

The antibody showed no cross-reactivity with soluble proteins and specifically labeled membrane-bound QUA3 in Arabidopsis and heterologous systems .

Subcellular Localization

Advanced imaging techniques confirmed QUA3’s Golgi localization:

• Co-localization: 90% overlap with the Golgi marker Man1-mRFP in Arabidopsis protoplasts .

• Immunogold EM: Gold particles concentrated on Golgi cisternae in Arabidopsis PSBL cells (Fig. 4) .

• No association with PVC, COPII, or COPI vesicles was observed .

Enzymatic Role in Homogalacturonan Methylation

QUA3 exhibits methyltransferase activity critical for pectin modification. Key findings include:

Table 2: Methyltransferase Activity in QUA3-OE vs. Wild-Type Cells

Overexpression of QUA3 increased activity by 58%, while GFP fusion abolished substrate specificity, suggesting the C-terminus’s role in enzymatic function .

Functional Studies

• Loss-of-function mutants: Displayed reduced pectin methylation and cell adhesion defects .

• Overexpression lines: Enhanced methyltransferase activity but no phenotypic changes under standard conditions .

Technical Utility

• Membrane protein studies: QUA3 antibodies enabled Golgi-specific protein trafficking analysis .

• Transgenic validation: Used to confirm QUA3-GFP expression and localization in tobacco BY-2 cells .