PSPH Antibody

PSPH Structure and Function

Phosphoserine phosphatase (PSPH) is a 225 amino acid enzyme that catalyzes the final irreversible step in the biosynthesis of L-serine from carbohydrates through the dephosphorylation of O-phospho-L-serine to L-serine . This Mg2+-dependent enzyme plays a critical role in the phosphorylated pathway of serine biosynthesis, contributing a major portion of endogenous L-serine . The importance of this pathway extends beyond amino acid production, as L-serine serves as a precursor for the biosynthesis of diverse compounds including neurotransmitters, glycolipids, and thymidine .

The three-dimensional structure of PSPH reveals a complex arrangement featuring an α-helical bundle domain that undergoes environmental changes between open and closed conformations. These conformational changes are crucial for substrate recognition and hydrolysis through local rearrangements at the active site . PSPH is highly expressed in periventricular neural progenitors in the embryonic brain, suggesting a significant role in neural stem cell proliferation and development .

PSPH Antibody Overview

PSPH antibodies are immunoglobulins specifically designed to bind to the PSPH protein with high affinity and specificity. These antibodies serve as invaluable tools for researchers studying PSPH expression, localization, and function across various experimental contexts. They are produced through immunization of host animals (typically rabbits or mice) with PSPH protein or peptide fragments, resulting in the generation of antibodies that specifically recognize different epitopes of the PSPH protein .

Different types of PSPH antibodies are available for research purposes, including monoclonal antibodies derived from single antibody-producing cell lines, polyclonal antibodies harvested from the serum of immunized animals, and more recently, recombinant monoclonal antibodies produced through genetic engineering technologies .

Monoclonal PSPH Antibodies

Monoclonal PSPH antibodies are derived from single B-cell clones, ensuring high specificity and consistency between batches. Several commercial monoclonal PSPH antibodies are available, each with unique specifications optimized for specific applications.

For example, the mouse monoclonal PSPH antibody (H-11) is an IgG2b κ antibody that detects PSPH in mouse, rat, and human samples through applications including western blotting, immunoprecipitation, immunofluorescence, and ELISA . Similarly, the mouse monoclonal PSPH antibody (H-10) is an IgG1 κ antibody available in both unconjugated and various conjugated forms, including agarose, horseradish peroxidase (HRP), phycoerythrin (PE), fluorescein isothiocyanate (FITC), and multiple Alexa Fluor conjugates .

Another example is the mouse monoclonal antibody (clone 3C1) that targets amino acids 1-100 of the PSPH protein and is suitable for western blotting and ELISA applications with recombinant GST-tagged PSPH .

Polyclonal PSPH Antibodies

Polyclonal PSPH antibodies recognize multiple epitopes on the PSPH protein, potentially providing higher sensitivity at the cost of some specificity compared to monoclonal antibodies. The rabbit polyclonal PSPH antibody (14513-1-AP) from Proteintech has been validated for western blotting, immunohistochemistry, immunofluorescence, immunoprecipitation, and ELISA applications with human, mouse, and rat samples .

This antibody has been cited in numerous publications and shows reactivity with various cell lines including A375, U-87 MG, HL-60, MCF-7, and SK-BR-3 cells, as well as rat liver tissue . For immunohistochemistry applications, it is recommended to use antigen retrieval with TE buffer pH 9.0 or alternatively with citrate buffer pH 6.0 .

Recombinant PSPH Antibodies

Recombinant PSPH antibodies represent the cutting edge of antibody technology, offering unrivaled batch-to-batch consistency through in-house recombinant production methods. The rabbit recombinant monoclonal antibody (84899-2-PBS) from Proteintech is provided in a conjugation-ready format in PBS buffer (BSA and azide-free) at a concentration of 1 mg/mL .

This antibody is part of a matched antibody pair (84899-2-PBS capture and 84899-1-PBS detection) validated for cytometric bead array applications . The recombinant production method ensures consistent quality, easy scale-up, and security of future supply, making it an ideal choice for standardized assays requiring high reproducibility.

Western Blot (WB)

PSPH antibodies are widely used in western blotting to detect and quantify PSPH protein expression in cell and tissue lysates. The expected molecular weight of PSPH is approximately 25 kDa, though observed weights may range from 25-28 kDa depending on the specific antibody and experimental conditions .

For example, the rabbit polyclonal antibody (ab211418) demonstrated specific binding to PSPH in western blot analysis, showing a clear band at 25 kDa in wild-type A549 cell lysates while no signal was observed at this size in PSPH knockout cell lines . This antibody was used at a dilution of 1/1000 and shown to be specific for human PSPH .

Similarly, the polyclonal antibody 14513-1-AP has been validated for western blotting at dilutions between 1:500-1:3000 and has been cited in at least 25 publications using this application .

Immunohistochemistry (IHC)

PSPH antibodies are valuable tools for visualizing the localization and expression patterns of PSPH protein in tissue sections. For formalin-fixed, paraffin-embedded (FFPE) tissues, different antibodies and protocols have been validated.

In a neuroblastoma study, researchers used a PSPH antibody (14513-1-AP) at a dilution of 1:100 for immunohistochemical staining of FFPE tissue sections . The sections were boiled in tris-EDTA buffer (pH 8.0) for antigen retrieval, incubated with the primary antibody overnight at 4°C, and visualization was achieved using diaminobenzidine with hematoxylin counterstaining .

Similarly, in a gastric cancer study, researchers used the PSPH antibody (ab224110) at a 1:100 dilution following citrate antigen repair buffer (pH 6.0) treatment and endogenous peroxidase blocking with 3% hydrogen peroxide . The scoring of PSPH expression was determined by three pathologists who evaluated both the proportion of stained tumor cells and staining intensity .

Immunofluorescence (IF/ICC)

PSPH antibodies are also utilized for immunofluorescence and immunocytochemistry applications to visualize PSPH in cultured cells. The polyclonal antibody 14513-1-AP has been validated for IF/ICC at dilutions of 1:50-1:500, with positive detection demonstrated in HepG2 cells .

This application allows researchers to observe the subcellular localization of PSPH and co-localize it with other proteins of interest through multi-color immunofluorescence, providing insights into potential protein-protein interactions and functional relationships.

Immunoprecipitation (IP)

Immunoprecipitation using PSPH antibodies enables the isolation and enrichment of PSPH protein complexes from cell lysates, facilitating the study of protein-protein interactions and post-translational modifications. The polyclonal antibody 14513-1-AP has been validated for IP using 0.5-4.0 μg of antibody for 1.0-3.0 mg of total protein lysate, with positive detection demonstrated in HL-60 cells .

ELISA

PSPH antibodies are employed in enzyme-linked immunosorbent assays (ELISA) for quantitative detection of PSPH protein in biological samples. Multiple antibodies including the mouse monoclonal antibody (ANT-399) have been validated for ELISA applications .

Of particular interest is the recombinant monoclonal antibody (84899-2-PBS) which forms part of a matched antibody pair specifically designed for cytometric bead array applications, offering a high-throughput method for PSPH quantification .

PSPH and Neuroblastoma

In vitro experiments demonstrated that high expression of PSPH significantly promoted cell growth and metastasis in neuroblastoma cell lines . Further analysis using the ESTIMATE algorithm revealed that high PSPH expression was negatively associated with CD8+ T cells, macrophages, and neutrophils in the tumor microenvironment, which may contribute to the poor survival outcomes observed in patients with high PSPH expression (p < 0.0001, p = 0.0005, and p = 0.0004, respectively) .

PSPH and Gastric Cancer

Similar to findings in neuroblastoma, PSPH expression has been identified as a prognostic biomarker in gastric cancer. Immunohistochemical analysis revealed higher PSPH expression in gastric cancer patients compared to normal individuals, with high expression correlating with poor survival outcomes .

Mechanistic studies suggested that the poor prognosis associated with high PSPH expression may be mediated through its impact on the tumor immune microenvironment. Specifically, patients with higher PSPH expression exhibited lower ESTIMATE, stromal, and immune scores .

Using the Cibersort algorithm, researchers found that the abundance of resting NK cells, activated memory CD4 T cells, and M0 macrophages was high in the high PSPH expression group, whereas memory B cells and activated or resting mast cells were low . These findings suggest that PSPH may participate in regulating the tumor immune microenvironment in gastric cancer, potentially influencing patient outcomes through immune-mediated mechanisms.

PSPH and Other Cancers

Beyond neuroblastoma and gastric cancer, elevated PSPH expression has been correlated with prognosis in multiple other malignancies. Research has identified augmented PSPH levels as prognostically significant in cutaneous squamous cell carcinoma, breast cancer, non-small cell lung cancer, colorectal cancer, and hepatocellular carcinoma .

In hepatocellular carcinoma specifically, PSPH has been shown to induce cell autophagy and promote cell proliferation and invasion in the Huh7 cell line via the AMPK/mTOR/ULK1 signaling pathway . This suggests that PSPH may play an active role in promoting tumor progression rather than serving merely as a passive biomarker.

Table 2: PSPH Expression and Survival Outcomes in Different Cancers

PSPH and Immune Response

One of the most intriguing aspects of recent PSPH research is its relationship with the tumor immune microenvironment. Multiple studies have demonstrated correlations between PSPH expression and immune cell infiltration patterns in various cancers, suggesting potential immunomodulatory functions of this metabolic enzyme.

In neuroblastoma, high PSPH expression was negatively associated with CD8+ T cell, macrophage, and neutrophil infiltration, all of which are important components of anti-tumor immunity . This negative association with immune effector cells may partially explain the poor survival outcomes observed in patients with high PSPH expression.

Similarly, in gastric cancer, PSPH expression was inversely correlated with ESTIMATE, stromal, and immune scores . Detailed analysis revealed that high PSPH expression was associated with altered abundance of specific immune cell populations, including resting NK cells, activated memory CD4 T cells, M0 macrophages, memory B cells, and mast cells .

These findings suggest a potential PSPH-immune axis in cancer progression, whereby PSPH expression may influence tumor growth and patient outcomes through modulation of the immune microenvironment. This emerging understanding opens new avenues for therapeutic intervention, potentially combining PSPH inhibitors with immunotherapy to enhance treatment efficacy.

Table 3: PSPH Expression and Immune Cell Infiltration