MMADHC Antibody, Biotin conjugated

Introduction to MMADHC Antibody, Biotin Conjugated

The MMADHC antibody, biotin conjugated, is a specialized immunological tool designed for detecting the methylmalonic aciduria and homocystinuria type D homolog (MMADHC) protein. This protein plays a critical role in intracellular vitamin B12 (cobalamin) metabolism, directing cobalamin to cytosolic and mitochondrial enzymes for the synthesis of methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl) . Biotin conjugation enhances the antibody’s utility in detection-based assays by enabling high-affinity binding to streptavidin-linked reporters, facilitating applications such as ELISA, immunohistochemistry (IHC), and flow cytometry .

Role in Cobalamin Trafficking

MMADHC acts as an adaptor protein, bridging MMACHC (cblC) and downstream enzymes like methionine synthase (MS) and methylmalonyl-CoA mutase . The biotin-conjugated antibody enables precise localization studies, revealing MMADHC’s dual localization in mitochondrial and cytosolic compartments . Mutations in MMADHC disrupt cobalamin distribution, leading to combined methylmalonic aciduria and homocystinuria (cblD disorder) .

Disease Mechanism Studies

• Premature Termination Codons (PTCs): The antibody detects truncated MMADHC isoforms in cblD patients, such as those caused by c.24-25delAG or R54X mutations, which impair cobalamin cofactor synthesis .

• Subcellular Localization: MMADHC’s N-terminal mitochondrial targeting sequence (residues 1–12) and C-terminal nitroreductase-like domain (residues 108–296) are critical for its function, as shown via immunoblotting and IHC .

Sensitivity and Specificity

• ELISA: Linear detection range of 2–250 ng/mL with a biotin-streptavidin amplification system .

• Western Blot: Identifies full-length MMADHC (~33 kDa) and disease-associated truncations (e.g., M62-MMADHC and M116-MMADHC) .

• Immunohistochemistry: Validated in formalin-fixed paraffin-embedded (FFPE) tissues, showing cytoplasmic and mitochondrial staining patterns .

Diagnostic Utility

The antibody aids in diagnosing cblD disorder by identifying MMADHC expression defects in patient fibroblasts or liver biopsies . For example, homozygous c.24-25delAG mutations result in undetectable MMADHC via immunoblotting .

Therapeutic Development

Biotin-conjugated MMADHC antibodies are used in high-throughput screens to evaluate translational readthrough therapies for PTC mutations . Aminoglycosides like gentamicin restore full-length MMADHC expression in vitro, offering potential treatment avenues .