Oligo-isoadenylate-Synthetase

OLIGO-ISOADENYLATE SYNTHESIS AND ACTIVATION OP NUCLEASE P A. Oligo-isoadenylate-Synthetase E 

During purification of the protein synthesis inhibitors from interferon-treated cells, the dsENA-ATP activated protein kinase PK-i, was separated from another dsRNA-ATP dependent activity. 

In extracts from control cells, F can be made to inhibit translation if p-urified iso-A trimers are added. The nucleotide by itself inhibits translation only to a small extent jmless factor P is added. With F, concentrations of 1-10x10 9m trimers become efficient inhibitors (Table 2). Iso-A dimers had 10-20 times less activity, but tetramers were as active as trimers 

P is present in untreated cell extracts, but its activity may be higher by 1.J-2 fold after interferon treatment (Table 2). This change is small as compared to the more than 10-fold increase in iso-A synthetase E activity after interferon (IO). P is present 

Oligo-isoadenylate activated nuclease activity of factor F. T I globin mRNA (0.5 M g) incubated (18) 50 min, 300C with 0.5 ixg F (PC-purified) and 0.16 pmoles, iso-A trimers (X) was analyzed by polyacrylamide gel electrophoresis, 7 iirea. Scanning of autoradiography is shown. Arrow shows direction of migration. 

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The following are recent reviews on the molecular and physical properties of this ligase (or, 2, 5 -oligo(A) polymerase or oligo-isoadenylate synthetase E). 

Figure 3 Separation of various translation regulatory activities on DEAE cellulose. Cell sap from interferon-treated cultures was fractionated and assayed on mengo RNA translation (as in Table 2) in S10 from control (c) and interferon-treated cells (int) with O.O4 M g/ml dsENA. Activity without fraction = 1. Oligo-isoadenylate synthetase E (IO), factor F (18). Protein phosphatase (P) and protein kinase activator A, are discussed in the text.

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