Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.4.17 (adenosine deaminase)
 5,206 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has been proposed that the pathogenesis of melanoma proceeds through multiple stages, ranging from benign proliferation of melanocytic cells to acquisition of the capacity to invade tissues and metastasize. During investigations of cell surface antigens expressed by melanocytes and melanoma, we identified an antigen system that was expressed by cultured normal melanocytes but not by melanoma cell lines. mAbs against this antigen detected a 120-kD cell surface glycoprotein on melanocytes. This molecule had been identified previously as the binding protein for adenosine deaminase (ADAbp). ADAbp was expressed by 51 melanocyte cell lines derived from normal fetal, newborn, and adult skin and adult choroid, but not by 102 melanoma cell lines derived from primary and metastatic lesions. Studies with radiolabeled bovine adenosine deaminase, confirmed that melanocytes expressed binding sites for adenosine deaminase, but no binding sites were detected on cultured melanoma cells. Further studies showed that ADAbp+ melanocytes became ADAbp- upon malignant transformation in vitro. Immunohistochemical studies on a panel of frozen tissues demonstrated reactivity of anti-ADAbp mAbs with epidermal melanocytes and benign junctional nevi, but not with potentially premalignant dysplastic nevi or primary/metastatic melanoma lesions. These studies demonstrate that ADAbp expression is lost with malignant transformation of melanocytes, presumably at an early stage in the transformation process.
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PMID:Cell surface antigens of human melanocytes and melanoma. Expression of adenosine deaminase binding protein is extinguished with melanocyte transformation. 289 80

CD26, a 110-kDa cell surface glycoprotein, exhibits dipeptidyl peptidase IV enzyme activity and plays an important role in T cell costimulation. In the present study, we examined both the exact adenosine deaminase (ADA) binding domain on CD26 and the functional consequences of mutated CD26 transfectants that were deficient for cell surface ADA. Using CD26 deletion, human-rat swap, and point mutations, we found that the residues of L340, V341, A342, and R343 on the CD26 molecule were essential amino acids for ADA binding. When these amino acids were mutated and transfected into Jurkat cells, the resultant CD26 transfectants expressed only CD26, not ADA, on the cell surface. The amount of IL-2 produced by wild-type and mutated CD26 transfectants was almost the same following stimulation with anti-CD3 plus PMA. However, the mutated CD26 transfectants were much more sensitive to the inhibitory effect of adenosine on IL-2 production than were the wild CD26 transfectants. These data suggest that ADA on the cell surface does not directly involve T cell activation. Conversely, CD26 alone does not result in modulating the inhibitory effect of adenosine. Only the ADA bound to CD26 on the cell surface was functional and could counteract the inhibitory effect of elevated extracellular adenosine.
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PMID:Determination of adenosine deaminase binding domain on CD26 and its immunoregulatory effect on T cell activation. 955 Apr 6