期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1986
卷号：83
期号：11
页码：4030-4034
DOI：10.1073/pnas.83.11.4030
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Nucleoside kinases catalyze the initial step leading to the accumulation of deoxypurine nucleotides that occurs in patients with inherited deficiencies of adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4 ) and purine-nucleoside phosphorylase (purine-nucleoside:orthophosphate ribosyltransferase, EC 2.4.2.1 ). This accumulation is thought to interfere with DNA synthesis in lymphocytes and, thus, to cause the immune defects associated with these enzymopathies. However, there is controversy about the identity of the nucleoside kinases that are responsible for intracellular phosphorylation of deoxyadenosine in adenosine deaminase deficiency and deoxyguanosine in purine nucleoside phosphorylase deficiency. To distinguish the nucleoside kinases present in T and B lymphoblastoid cells, we have coupled discontinuous PAGE with autoradiography. This procedure showed that deoxycytidine kinase (NTP:deoxycytidine 5'-phototransferase, EC 2.7.1.74 ), deoxyadenosine kinase (ATP:deoxyadenosine 5'-phosphotransferase, EC 2.7.1.76 ), and adenosine kinase (ATP:adenosine 5'-phosphotransferase, EC 2.7.1.20 ) are all present in both T and B lymphoblasts. While adenosine kinase is expressed at nearly equal levels in B and T cells, the deoxynucleoside kinases are expressed at much lower levels in B cells than in T cells. The autoradiographic data agreed with assays of the nucleoside kinase activities. Molecular weights were determined by using 5-10% polyacrylamide gels. Mr values were 29,000 for adenosine kinase, 41,000 for deoxyadenosine kinase, and 53,000 for deoxycytidine kinase and its isozyme. The reduced expression of deoxycytidine and deoxyadenosine kinases in B lymphoblasts may account for the lower accumulation of deoxypurine nucleotides in B cells as compared with T cells.
