CD109 Antibody

Introduction to CD109 Antigen

CD109 is a glycosylphosphatidylinositol (GPI)-linked cell surface glycoprotein and a member of the alpha2-macroglobulin/complement gene family. It has a predicted molecular weight of approximately 162 kDa, though some studies report it as a 150-170 kDa protein . This protein contains a thioester motif characteristic of alpha-2-macroglobulin and undergoes autolytic cleavage under denaturing conditions . The human CD109 gene encodes a protein identified as Q6YHK3 in the UniProt database, with mature human CD109 spanning from Val22 to Ser1268 (with variations noted at positions Tyr703Ser and Thr1241Met) .

CD109 is expressed in various tissues and cell types, displaying a complex distribution pattern that suggests diverse physiological roles. It has been detected in CD34+ and CD34- bone marrow stem cells, CD34+ cells in the fetal liver, acute myeloid leukemia cells, T cell lines, activated T lymphoblasts, activated platelets, and endothelial cells . In adult tissues, CD109 is widely expressed in the brain, uterus, heart, lung, and trachea . Notably, CD109 expression is upregulated on PHA-stimulated T cells .

Types of CD109 Antibodies

CD109 antibodies are available in multiple formats to accommodate diverse research applications. The primary classification includes:

Table 1: Key Types of CD109 Antibodies

Monoclonal antibodies offer superior specificity and consistency for targeted applications, with clones like W7C5 and TEA 2/16 being commonly used in human CD109 research . The mouse monoclonal antibody TEA 2/16 specifically recognizes CD109, also known as C3 and PZP-like alpha-2-macroglobulin domain-containing protein 7 (CPAMD7), Gov platelet alloantigens, or 150 kDa TGF-beta-1-binding protein . Novel monoclonal antibodies such as KU42.33C and KU43.13A have been developed specifically for detecting CD109 in pancreatic cancer research .

Conjugated Antibodies

Many CD109 antibodies are available with various conjugations to facilitate detection in different experimental settings:

Table 2: Common CD109 Antibody Conjugations

Applications of CD109 Antibodies

CD109 antibodies serve multiple research purposes across various experimental platforms. Their utility spans from protein detection to functional studies.

Detection Methods

Table 3: Applications of CD109 Antibodies with Typical Dilutions

In Western blot analyses, CD109 antibodies typically detect a specific band at approximately 161-190 kDa, as demonstrated with the U-87 MG human glioblastoma/astrocytoma cell line . For flow cytometry applications, CD109 antibodies have been validated on various cell types, including A431 human epithelial carcinoma cell lines . Immunohistochemistry applications have revealed CD109 expression in tissues such as human squamous cell carcinoma and human placenta .

Sample Preparation Considerations

For optimal CD109 antibody performance, proper sample preparation is essential:

• Western blot analyses typically employ reducing conditions using appropriate buffer systems

• For flow cytometry, 1 × 10^6 cells in a 100-µl experimental sample is typically recommended

• Immunohistochemistry protocols often utilize immersion-fixed paraffin-embedded sections with overnight incubation at 4°C

• Storage recommendations generally advise keeping antibodies undiluted between 2°C and 8°C, with PE-conjugated antibodies requiring protection from prolonged light exposure

CD109 Antibodies in Research

CD109 antibodies have facilitated numerous research discoveries regarding the biological functions and pathological implications of CD109.

Biological Functions of CD109

Research utilizing CD109 antibodies has revealed that CD109 plays significant roles in various biological processes:

1. TGF-β Signaling Regulation: CD109 binds to and negatively regulates signaling of transforming growth factor beta (TGF-β) . It has been identified as part of the TGF-β receptor system in human keratinocytes . Studies show CD109 specifically interacts with TGF-β1 and TβRI, and generally with TβRII and betaglycan, inhibiting TGF-β signaling by promoting internalization and degradation of the TβR complex via caveolar endosomes .

2. Hematopoiesis: While its precise role in hematopoiesis remains to be fully elucidated, CD109 has been detected on long-term adult bone marrow cultured cells, where it is co-expressed with CD34 and CD90 .

3. Platelet Function: CD109 has been implicated in refractoriness to platelet transfusion, neonatal alloimmune thrombocytopenia, and post-transfusion purpura .

CD109 in Disease Pathology

CD109 antibodies have been instrumental in uncovering the role of CD109 in various pathological conditions:

Table 4: CD109 Expression in Pathological Conditions

Recent research has uncovered that CD109 may function as a "gatekeeper" of the epithelial phenotype by inhibiting TGF-β-induced epithelial-mesenchymal transition (EMT) . In the absence of CD109, TGF-β-induced EMT proceeds unopposed, resulting in epithelial cells acquiring a mesenchymal phenotype . This function has significant implications for cancer progression and metastasis.

Recent Research Findings

Novel monoclonal antibodies against CD109, such as KU42.33C and KU43.13A, have been developed for pancreatic cancer research . While treatment with these naked antibodies alone did not affect tumor cell growth or migration in vitro, they proved to be excellent tools for determining CD109 expression in tumor specimens . Of particular interest, mAb KU42.33C demonstrated utility in Western blot and immunohistochemistry applications for detecting CD109 in pancreatic carcinoma tissues .

Research utilizing CD109 knockout models has revealed that CD109 loss globally affects gene expression and signaling pathways . Recombinant human CD109 (rhCD109) has been shown to rescue the epithelial phenotype of CD109-knockout squamous cell carcinoma cells, confirming the protein's role in maintaining epithelial characteristics .

Quality Control and Validation

Proper validation of CD109 antibodies is essential for reliable experimental results. Quality control measures typically include:

• Testing reactivity with recombinant CD109 protein in direct ELISAs

• Verifying specificity in Western blot analyses using positive control cell lines like U-87 MG human glioblastoma/astrocytoma or A431 human epithelial carcinoma

• Confirming appropriate cellular localization in immunohistochemistry applications

• Using appropriate isotype controls at the same concentration as the antibody of interest in flow cytometry applications