PEX11-1 Antibody

What is the biological function of PEX11 proteins?

PEX11 proteins play a crucial role in promoting peroxisome division in eukaryotic cells. Research has demonstrated that PEX11 proteins are unique in their ability to drive peroxisome division independently of peroxisomal metabolism. Experimental evidence shows that overexpression of PEX11 significantly increases peroxisome abundance, while deletion or knockdown causes a pronounced reduction in peroxisome numbers. The process involves morphological changes to peroxisomes, beginning with elongation followed by division, ultimately resulting in increased peroxisome abundance. This fundamental role in organelle biogenesis makes PEX11 proteins central to peroxisome homeostasis in cells .

How many PEX11 isoforms exist and how do they differ functionally?

Mammals express at least two primary forms of PEX11: PEX11α and PEX11β, both functioning as integral peroxisomal membrane proteins. A third isoform, PEX11γ, has also been identified. These isoforms exhibit tissue-specific expression patterns and potentially distinct functions. PEX11α is highly expressed in the kidney and liver, while PEX11β appears to have broader expression. Functional studies indicate that PEX11α deficiency can impair peroxisome elongation, leading to reduced functional peroxisomes and diminished fatty acid oxidation capacity, eventually resulting in steatosis . In fungi like Aspergillus oryzae, two orthologous PEX11 genes (Aopex11-1 and Aopex11-2) have been identified, with Aopex11-1 playing a predominant role in peroxisomal function and proliferation . Plants like Arabidopsis contain multiple PEX11 isoforms that all localize to peroxisomes, suggesting evolutionary diversification of this protein family across kingdoms .

What is the molecular weight of PEX11 proteins?

The calculated molecular weight of human PEX11A is approximately 28 kDa, which corresponds to the observed molecular weight in experimental systems . Similarly, human PEX11γ has a calculated molecular weight of 27 kDa (from a 241 amino acid sequence) and is typically observed at 27 kDa in Western blot analyses . This consistency between predicted and observed molecular weights is important for antibody validation and protein identification in experimental settings.

What are the optimal applications for PEX11 antibodies in research?

Based on validated research applications, PEX11 antibodies are primarily used for:

It is recommended to optimize dilutions for each specific experimental system, as antibody performance can be sample-dependent. For PEX11A antibody (15481-1-AP), positive Western blot signals have been detected in mouse kidney tissue, while PEX11G antibody (15744-1-AP) shows reactivity in PC-12 cells, human testis tissue, and mouse testis tissue .

How should researchers optimize PEX11 antibody conditions for Western blotting?

For optimal Western blot results with PEX11 antibodies:

• Sample preparation: Use appropriate lysis buffers that effectively solubilize membrane proteins while preserving epitope integrity.

• Protein loading: Load 20-40 μg of total protein per lane for cell lysates.

• Dilution optimization: Begin with the manufacturer's recommended range (e.g., 1:1000-1:4000 for PEX11A antibody) and adjust based on signal strength.

• Blocking conditions: Use 5% non-fat milk or BSA in TBST for 1 hour at room temperature.

• Incubation time: Primary antibody incubation at 4°C overnight typically yields optimal results.

• Detection method: HRP-conjugated secondary antibodies with enhanced chemiluminescence provide sensitive detection.

Always include appropriate positive controls, such as mouse kidney tissue for PEX11A antibody or PC-12 cells for PEX11G antibody validation .

What experimental approaches can be used to study PEX11-mediated peroxisome division?

To investigate PEX11-mediated peroxisome division, researchers can employ several methodological approaches:

• Overexpression studies: Transfect cells with PEX11 expression constructs (e.g., pcDNA3-PEX11βmyc) and observe peroxisome morphology changes over time. Within 1.5-2 hours after microinjection, PEX11β localizes to peroxisomes; by 4-8 hours, peroxisomes begin to elongate; and by 24-48 hours, a significant increase in peroxisome abundance occurs .

• Knockout/knockdown studies: Generate PEX11-deficient cell lines or animal models to assess the impact on peroxisome abundance and morphology. Research has shown that PEX11β−/− cells exhibit approximately half the peroxisome abundance of wild-type cells (128 ± 32 vs. 230 ± 52 peroxisomes per section) .

• Time-course analysis: Monitor peroxisome morphology changes using fluorescence microscopy with peroxisomal markers at various time points after PEX11 manipulation.

• Electron microscopy: Analyze ultrastructural changes in peroxisome morphology and abundance.

• Dual localization analysis: Use fluorescently tagged peroxisomal markers together with PEX11 to assess co-localization patterns and morphological changes.

How does PEX11 function independently of peroxisomal metabolism?

Studies in human cells deficient in peroxisomal β-oxidation enzymes (PBD005 cells) revealed that PEX11β overexpression still induced a dramatic 30-fold increase in peroxisome abundance (979 ± 388 peroxisomes per section) compared to untransfected cells (32 ± 16 peroxisomes per section). Since these cells lack functional peroxisomal metabolic pathways, this observation provides strong evidence that PEX11's division-promoting activity operates through a direct mechanism, rather than as a secondary consequence of its metabolic functions .

Furthermore, studies in PEX11β−/− mice showed reduced peroxisome abundance even when cells were grown in serum-free medium lacking fatty acids, further supporting the model that PEX11 proteins directly participate in the peroxisome division process .

What is the relationship between PEX11 and specialized peroxisomal structures like the Woronin body?

In filamentous fungi, Woronin bodies are specialized peroxisome-derived organelles that plug septal pores upon hyphal damage to prevent cytoplasmic bleeding. Recent research has revealed a critical connection between PEX11 and Woronin body biogenesis.

Studies in Aspergillus oryzae demonstrated that disruption of the Aopex11-1 gene impaired Woronin body function, leading to excessive cytosol loss upon hyphal injury. Electron microscopy of ΔAopex11-1 strains revealed Woronin bodies that remained associated with peroxisome-like organelles, failing to fully differentiate. Dual localization analysis of peroxisome and Woronin body proteins showed that the Woronin body protein AoHex1 was abnormally distributed at the periphery of enlarged peroxisomes or at junctions in dumbbell-shaped peroxisomes in the mutant strain .

This research represents the first description of Pex11's role in Woronin body differentiation, highlighting a specialized function beyond general peroxisome proliferation in filamentous fungi. This finding has implications for understanding organelle biogenesis and differentiation pathways in eukaryotic cells .

How do the three kinetically distinct steps of PEX11β-induced peroxisome division occur?

PEX11β-induced peroxisome division follows a three-step process with distinct kinetic phases, as determined by immunofluorescence microscopy experiments:

• Initial localization (1.5-2 hours post-transfection): PEX11β localizes to peroxisomes of normal abundance and morphology.

• Peroxisome elongation (4-8 hours post-transfection): Peroxisomes in PEX11β-expressing cells begin to elongate, forming tubular structures.

• Peroxisome division (24-48 hours post-transfection): A large increase in peroxisome abundance occurs as elongated peroxisomes undergo fission.

This temporal sequence suggests a coordinated process where PEX11β first alters peroxisome membrane properties to facilitate elongation, followed by recruitment or activation of the division machinery that completes the fission process. The specific molecular mechanisms governing the transition between these phases remain an active area of research .

What are common issues when using PEX11 antibodies and how can they be resolved?

When troubleshooting PEX11G antibody in IHC applications, researchers should note that antigen retrieval with TE buffer pH 9.0 is suggested, though citrate buffer pH 6.0 may serve as an alternative . For storage stability, maintaining antibodies at -20°C with 0.02% sodium azide and 50% glycerol (pH 7.3) is recommended to preserve activity .

How should researchers interpret changes in PEX11 expression in different experimental conditions?

When interpreting changes in PEX11 expression:

• Consider tissue-specific expression patterns: PEX11A is normally highly expressed in kidney and liver tissues .

• Correlate expression with peroxisome morphology: Increased PEX11 expression typically precedes changes in peroxisome morphology and abundance.

• Evaluate metabolic context: While PEX11 functions independently of metabolism, metabolic conditions can influence peroxisome dynamics and PEX11 expression.

• Distinguish between isoforms: Changes in specific PEX11 isoforms may have different physiological implications.

• Validate with multiple approaches: Combine protein level analysis (Western blot) with functional assays and morphological studies (microscopy).

What are the emerging roles of PEX11 beyond peroxisome division?

Recent research has expanded our understanding of PEX11 functions beyond peroxisome division:

• Metabolic regulation: While PEX11 promotes peroxisome division independently of metabolism, loss of PEX11 affects multiple unrelated peroxisomal metabolic activities, suggesting potential roles in membrane structure or dynamics that indirectly influence metabolic functions .

• Specialized organelle differentiation: The discovery of PEX11's role in Woronin body differentiation in filamentous fungi opens avenues for investigating its participation in other specialized peroxisome-derived structures .

• Membrane remodeling: PEX11's ability to induce membrane elongation suggests potential functions in membrane curvature and remodeling that may extend beyond peroxisomes.

• Human disease relevance: A homozygous non-sense mutation in the PEX11β gene has been associated with a novel defect in peroxisome division, suggesting clinical importance of PEX11 function .

Future research will likely focus on these emerging roles and their implications for peroxisome biology, cellular metabolism, and human health.

How do plant PEX11 isoforms compare to their mammalian counterparts?

Plants like Arabidopsis possess multiple PEX11 isoforms that all localize to peroxisomes but may have divergent functions. Cell biological and physiological assays with plants containing increased or decreased levels of Arabidopsis PEX11 proteins have provided insights into their roles in peroxisome proliferation and plant physiology.

Colocalization studies using fluorescent protein fusions (CFP-PEX11 and YFP-PTS1) in transgenic seedlings confirmed that all five Arabidopsis PEX11 proteins target to peroxisomes. Complementation experiments in yeast pex11 mutants with some Arabidopsis PEX11 isoforms through heterologous expression suggest functional conservation across species .