A guanyloribonuclease of mouse liver cytosol

Pantazaki, Αnastasia A.; Georgatsos, John G.

doi:10.1111/j.1432-1033.1990.tb19203.x

Cited by 2 publications

(1 citation statement)

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“…Whenever natural RNA of known sequence are used as substrates, a different picture emerges. Thus, of three RNAses purified from mouse liver cytosol, all of which hydrolyzed poly(C) and poly(U), but not poly(A) and poly(G), two were indeed shown to be pyrimidine specific [9] but one was found to be a guanosine-specific ribonuclease [21] when allowed to act on 5s RNA. In Tetrahyrnenapyriformis one of three RNases was also shown to hydrolyze RpN bonds in 5s RNA, even though all three preferred pyrimidine polynucleotides as substrates [13].…”

Section: Figurementioning

confidence: 99%

Ribonucleases of diverse specificities in rabbit brain nuclei

Pantopoulos

Georgatsos

1992

European Journal of Biochemistry

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A salt extract of rabbit brain nuclei contains three endoribonucleases, designated RNases Y, A and R, which produce acid-soluble products when incubated at near-neutral pH in the absence of metal ions. RNases Y and A yield products with the monoesterified phosphate at the 3' position, through 2',3'-(cyc1ic)phosphate intermediates. Oligonucleotides terminating with a 2',3'-(cyc1ic)phosphate are the end-products of the action of RNase R. Double-stranded substrates are highly resistant to the action of all enzymes. On the basis of limited hydrolysis of end-labelled 5s RNA, the three enzymes differ in their preference for the susceptible phosphodiester bond. Thus, RNase Y hydrolyses preferentially the YpN bond, RNase A the ApN bond and RNase R the RpU bond where R is guanosine in most cases. The advantages and disadvantages of using homopolyribonucleotides and dephosphorylated dinucleotides and trinucleotides in determining various aspects of the specificity of RNases are discussed.Interest in RNases has increased over the past few years for two main reasons. Ever-increasing numbers of RNases have been shown to possess biological actions, ostensibly unrelated to their nucleolytic activity. Thus RNases with angiogenic, immunosuppressive, anti-tumor, neurotoxic, etc., actions have been reported (for a review, see [I]). An everincreasing diversity of RNA metabolic processes has been discovered, whose operation require the involvement of RNases. Thus, in addition to the obvious function of these enzymes in degrading intracellular or extracellular RNA, their involvement in processes such as preRNA maturation and intron removal is well-documented. However, a large number of already discovered, not to mention the undiscovered, RNases await the assignment of function. Isolation of proper mutants should help in this respect, in the case of organisms readily subject to mutagenesis. With mammalian RNases, however, the situation is much more complex, and a logical approach, albeit not the only, would be the purification of the respective activities to a stage of catalytic purity (i.e. free of other nucleolytic activities as well as interfering enzymes such as phosphatases, deaminases, depurinases and so on) and characterization of specificity as a first step in the identification of the native substrate(s).In the present paper, we focus our attention on three RNases, extracted from nuclei of rabbit brain at high salt concentration, and show that these enzymes differ from one

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Section: Figurementioning

confidence: 99%