STT4 Antibody

What is STT4 and why is it important in research?

STT4 is a phosphatidylinositol 4-kinase that generates PtdIns(4)P at the plasma membrane, which is critical for actin cytoskeleton organization and cell viability . Unlike Pik1 (another PI 4-kinase that functions at the Golgi complex), STT4 has distinct roles in maintaining plasma membrane structure and function . Understanding STT4 function is important for elucidating fundamental cellular processes including phosphoinositide signaling, cell wall integrity, and membrane dynamics.

What experimental applications can STT4 antibodies be used for?

STT4 antibodies can be employed across multiple experimental platforms:

How should researchers distinguish between STT4 and other phosphatidylinositol kinases in their experiments?

Researchers should be aware that STT4 and Pik1 generate the same lipid product (PtdIns(4)P) but in different cellular locations. When designing experiments:

• Use subcellular fractionation to separate plasma membrane (STT4-enriched) from Golgi (Pik1-enriched) fractions

• Employ temperature-sensitive mutant strains for comparative studies (stt4ts vs pik1ts)

• Utilize co-localization with known markers: STT4 co-localizes with plasma membrane markers, while Pik1 co-localizes with Golgi markers

• When interpreting phenotypes, remember that STT4 inhibition affects actin organization and vacuole morphology, while Pik1 inhibition primarily disrupts secretion

How can researchers validate the specificity of STT4 antibodies?

Antibody validation is critical for ensuring experimental reproducibility . For STT4 antibodies, apply multiple validation methods:

• Genetic knockout controls: Test antibody reactivity in stt4 deletion strains (though complete deletion is lethal, temperature-sensitive mutants can serve as partial controls)

• Recombinant protein expression: Compare signal between STT4-overexpressing cells and control cells

• Immunodepletion: Pre-incubate antibody with purified STT4 protein to confirm signal loss

• Multiple antibody verification: Compare labeling patterns using antibodies targeting different STT4 epitopes

• siRNA knockdown: Verify reduced signal following STT4 knockdown

Researchers should document these validation steps thoroughly for publication, as journals increasingly require validation evidence .

What are the common pitfalls in STT4 antibody experiments and how can they be avoided?

What controls should be included in STT4 antibody experiments?

Essential controls include:

• Negative controls:

  • Primary antibody omission

  • Isotype-matched irrelevant antibody

  • Ideally, stt4ts mutant cells at restrictive temperature

• Positive controls:

  • Known STT4-expressing tissues/cells

  • Recombinant STT4-expressing cells

• Antibody specificity controls:

  • Pre-absorption with immunizing peptide/protein

  • Multiple antibodies against different STT4 epitopes

How can STT4 antibodies be used to study PIK patch assembly and dynamics?

PIK patches are unique cortical structures containing STT4 complexes . To study their assembly and dynamics:

• Use time-lapse microscopy with STT4 antibodies for immunofluorescence to track patch formation

• Combine with antibodies against known STT4 complex components (Ypp1, Efr3) to assess co-localization and complex assembly

• Implement super-resolution microscopy techniques to resolve PIK patch architecture

• For dynamic studies, consider live-cell compatible antibody fragments

Research has shown that each PIK patch contains approximately 30 STT4 molecules, forming oligomeric structures at the plasma membrane .

How do STT4 and STAT4 antibodies differ, and what precautions should researchers take to avoid confusion?

Despite similar names, STT4 and STAT4 are fundamentally different proteins:

To avoid confusion:

• Always verify antibody target specificity in product documentation

• Check epitope sequence to confirm target identity

• Verify molecular weight of detected protein (STAT4: 86 kDa)

• Use positive controls of known expression pattern

What methodological approaches can be used to study STT4 interactions with its regulatory proteins using antibodies?

STT4 functions in complex with regulatory proteins like Ypp1 and Efr3 . To study these interactions:

• Co-immunoprecipitation: Use STT4 antibodies to pull down associated proteins followed by western blot with antibodies to suspected partners

• Proximity ligation assay (PLA): Detect protein-protein interactions within 40nm using paired antibodies

• FRET analysis: Use fluorophore-conjugated antibodies to detect energy transfer between closely associated proteins

• Sequential immunoprecipitation: First precipitate with STT4 antibody, then with partner protein antibody to isolate specific complexes

Research has demonstrated that Efr3 is essential for recruiting both Ypp1 and STT4 to PIK patches, while Ypp1 interacts with distinct regions on STT4 necessary for assembly of the kinase complex .

How should researchers troubleshoot inconsistent STT4 antibody staining patterns?

When encountering variable STT4 staining patterns:

• Validate antibody specificity using multiple approaches described in section 2.1

• Optimize fixation protocol: Different fixatives (paraformaldehyde, methanol) may affect epitope accessibility

• Adjust membrane permeabilization: STT4's membrane association may require careful detergent selection

• Test different epitope retrieval methods: Heat-induced or enzymatic unmasking may improve detection

• Consider cell cycle stage: STT4 localization may vary throughout the cell cycle

• Verify experimental conditions: Temperature-sensitive STT4 mutants show distinct phenotypes at permissive versus restrictive temperatures

What are the optimal methods for detecting endogenous levels of STT4 protein?

Detecting endogenous STT4 presents challenges due to potentially low expression levels. Consider these approaches:

• Signal amplification systems: Tyramide signal amplification or polymer-based detection

• Sensitive western blot techniques: Extended exposure times with low-background substrates

• Enrichment prior to detection: Immunoprecipitation followed by western blot

• Subcellular fractionation: Concentrate plasma membrane fractions where STT4 is localized

• Enhanced microscopy techniques: Confocal microscopy with sensitive photomultipliers or image stacking

For fluorescence detection, three-dimensional reconstruction of z-stacks has been successfully employed to visualize STT4 PIK patches in yeast cells .

How can researchers use STT4 antibodies to investigate the relationship between phosphoinositide metabolism and sphingolipid signaling?

Research has identified synthetic lethality when both sphingolipid and PI4P synthesis are diminished . To investigate this relationship:

• Combined immunofluorescence: Use STT4 antibodies alongside markers for sphingolipid metabolizing enzymes

• Pharmacological approaches: Combine STT4 antibody staining with treatments affecting sphingolipid metabolism

• Genetic backgrounds: Examine STT4 localization and function in mutants of sphingolipid pathway genes (FEN1, SUR4)

• Lipidomic correlation: Correlate immunostaining intensity with quantitative lipidomics data

• Functional assays: Combine antibody-based detection with functional analysis of membrane trafficking

Studies have shown that STT4-generated PI4P and sphingolipid metabolism are functionally linked through the phosphoinositide effectors Slm1 and Slm2, which regulate actin organization and sphingolipid metabolism .

How can STT4 antibodies contribute to understanding phosphoinositide-mediated regulation of the actin cytoskeleton?

STT4-generated PtdIns(4)P is critical for actin cytoskeleton organization . Researchers can:

• Use STT4 antibodies in combination with actin visualization techniques to correlate STT4 localization with actin structures

• Examine STT4 distribution before and after actin-disrupting treatments

• Employ STT4 antibodies in conjunction with phosphoinositide sensors to correlate PI4P production with actin dynamics

• Investigate STT4 interaction with actin regulatory proteins through co-immunoprecipitation

Research in temperature-sensitive stt4 mutants has shown that these cells display random cortical actin patches throughout both mother and daughter cells, rather than restricting patches to the bud and septum as observed in wild-type cells .

What approaches can be used to study the role of STT4 in human or mammalian systems using antibody-based techniques?

While most STT4 research has been conducted in yeast, studying its mammalian homologs requires:

• Confirming antibody cross-reactivity with mammalian PI4Kα (STT4 homolog)

• Utilizing epitope mapping to identify conserved antibody recognition sites

• Validating specificity in mammalian cell systems using knockdown approaches

• Considering posttranslational modifications that may differ between yeast and mammals

Researchers should verify antibody specificity across species by performing western blots and immunofluorescence with appropriate positive and negative controls.

How might researchers use STT4 antibodies to investigate the relationship between phosphoinositide signaling and membrane trafficking disorders?

Given STT4's role in membrane dynamics, researchers can:

• Study STT4 localization in models of membrane trafficking disorders

• Examine co-localization with trafficking machinery components using dual immunofluorescence

• Investigate STT4 expression and localization changes in response to trafficking inhibitors

• Explore STT4 interaction with small GTPases that regulate membrane trafficking

Research has established distinct roles for PI 4-kinases in membrane trafficking events, with Pik1 being essential for secretion and Golgi function, while STT4 influences plasma membrane organization and vacuole morphology .

STAT4 Antibody: Comprehensive Research FAQ Collection

Based on the significant presence of STAT4 information in the search results, this additional FAQ section addresses STAT4 antibody applications to avoid confusion with STT4.

What is STAT4 and how does it differ from STT4?

STAT4 (Signal Transducer and Activator of Transcription 4) is a transcription factor involved in immune signaling pathways . Unlike STT4 (a phosphatidylinositol 4-kinase), STAT4:

• Functions as a transcription factor that transduces cytokine signals (IL-12, IL-23, and type I interferons) in T cells and monocytes

• Plays a critical role in T-helper type 1 and T-helper type 17 differentiation

• Has been implicated in multiple autoimmune diseases

• Has a molecular weight of approximately 86 kDa

What experimental applications can STAT4 antibodies be used for?

STAT4 antibodies have been validated for multiple applications:

How can researchers differentiate between phosphorylated and non-phosphorylated forms of STAT4?

STAT4 activation occurs via phosphorylation at Tyr693, which is critical for its function . To study STAT4 activation status:

• Use phospho-specific antibodies that selectively recognize STAT4 phosphorylated at Tyr693

• Compare with antibodies recognizing total STAT4 protein to calculate activation ratios

• Include appropriate controls (cytokine-stimulated vs. unstimulated cells)

• Consider time-course experiments to track phosphorylation dynamics

STAT4 is activated in response to IL-2 in natural killer (NK) cells, but not in T-cells, providing a useful cellular system for validation .

What are the key considerations for validating STAT4 antibodies?

Proper STAT4 antibody validation should include:

• Genetic approach: Test antibody in STAT4 knockout or knockdown samples

• Phospho-specificity verification: For phospho-STAT4 antibodies, treat samples with phosphatases to confirm signal loss

• Stimulation tests: Compare signals between unstimulated cells and cells treated with known STAT4 activators (IL-12, type I interferons)

• Cross-reactivity assessment: Test for potential cross-reactivity with other STAT family members

• Independent antibody verification: Compare results using antibodies recognizing different STAT4 epitopes

How can researchers use STAT4 antibodies to study autoimmune disease mechanisms?

STAT4 polymorphisms have been associated with multiple autoimmune diseases with systemic pathology . Researchers can:

• Use STAT4 antibodies for immunohistochemical studies of affected tissues in autoimmune disease models

• Examine STAT4 activation status in patient-derived samples

• Correlate STAT4 expression/activation with autoantibody levels

• Investigate STAT4 interactions with other immune regulators through co-immunoprecipitation

Research has shown that the STAT4 rs7574865 polymorphism is associated with systemic lupus erythematosus (OR = 1.52), rheumatoid arthritis (OR = 1.27), systemic sclerosis (OR = 1.38), and primary Sjögren's syndrome (OR = 1.32) .

What controls should be included when using STAT4 antibodies in research?

When working with STAT4 antibodies, include:

• Positive controls:

  • IL-12 stimulated cells (for phospho-STAT4)

  • Tissues with known STAT4 expression (spleen, lymphoid tissues)

  • Cell lines with confirmed STAT4 expression (Jurkat, A549, HeLa)

• Negative controls:

  • STAT4 knockout or knockdown samples

  • Unstimulated cells (for phospho-STAT4)

  • Isotype control antibodies

• Specificity controls:

  • Pre-incubation with immunizing peptide

  • Phosphatase treatment (for phospho-specific antibodies)