Anti-Human/Mouse PMEL (HMB-45) - Biotin (H7594-GRP)

Melanocytes are a cell type found in the skin and eyes that produce melanin. PMEL encodes a melanocyte-specific type I transmembrane glycoprotein that is subject to complex posttranslational processing, including modification, cleavage, trafficking and sorting to early melanosomes1, 2, 3. Melanosomes are a type of lysosome-related organelle that produce melanin pigment, and they progress through four stages of maturation3. PMEL plays an essential role in the structural organization of pre-melanosomes and is required for the formation of the internal matrix fibers (fibrils) that define the transition from Stage I to Stage II during melanosome morphogenesis1, 2, 3. Melanin is subsequently synthesized and deposited on those fibrils, resulting in a pigmented internal matrix in mature melanosomes3. Immunohistochemistry is widely used to differentiate melanomas, a cancer of melanocytes, from other tumors in clinical settings4. HMB-45 is commonly used in clinics to detect melanocytic tumors3 because it specifically stains the fibrillar matrix of pre-melanocytes and immature melanosomes5, 6. Although studies have shown that HMB-45 reacts with 56-100% of melanomas4, 7 as well as all cases of Spitz tumors 7 and atypical melanocytic hyperplasia, HMB-45 does not distinguish between benign and malignant melanocytic proliferations7. HMB-45 was generated in a BALB/c mouse using a portion of an axillary lymph node containing pigmented melanoma metastases as immunogen7. The spleen was removed, fused with NS-1 cells, and the resulting hybridoma lines screened against the same melanoma used as immunogen. Deletion of PMEL’s internal proline/serine/threonine-rich repeat (RPT) domain abolishes recognition by HMB-45 as well as PMEL’s capacity to form fibrils3.