The amino acid sequence of human ribonuclease 4, a highly conserved ribonuclease that cleaves specifically on the 3′ side of uridine

Abstract

. (1986a) Biochemistry 25,7255-72641 was purified from human plasma and its amino acid sequence was determined. This protein is a 119-residue single-chain polypeptidc cross-linked by four disulfide bonds and has an amino-terminal pyroglutaminyl residue. No post-translational modifications were observed during extensive sequence studies on peptide fragments, except for the amino-terminal pyroglutamic acid and a possible deamidation of Asn66. The protein is homologous to the pancreatic ribonucleases and angiogenin, but differs substantially from both of these proteins; the protein sequence has 43% identity with human pancreatic ribonuclease and 39% identity with human angiogenin, as compared to 35% identity between human angiogenin and pancreatic ribonuclease. It is referred to as RNase 4, based on the nomenclature currently used for the genes of pancreatic RNase (RNase 1) and the eosinophil-derived RNases (RNase 2 and RNase 3).Virtually all of the RNasc active-site componcnts, including the catalytic residues Hisl2, His1 19 and Lys41, are preserved. However, some invariant residues of RNase 1 arc replaced, e.g. Lys7 by arginine, Asp14 by histidine, and Pro42 by arginine. RNase 4 contains a unique two-residue deletion at the position corresponding to amino acids 77 and 78 of pancreatic RNase, and its carboxyterminal sequence is truncated at position 122. The deletion in angiogenin at position 21 is also found in RNase 4.RNase 4 is very similar to two RNases isolated from bovine and porcine liver, and together they form a new fanlily in the RNase superfamily. The degree of inter-species similarity (90%) is much greater than within the pancreatic RNase and angiogenin families, which suggests that this ribonuclease could possess a physiologically important function other than general RNA catabolism.The ribonucleases (RNases) constitute a group of enzymes for which a large amount of chemical information now exists. This information mostly relates to the pancreatic RNases; sequences from more than 40 species are known (Beintema and van der Laan, 1986). Recent investigations and discoveries have suggested that these enzymes are but one subdivision of a much broader superfamily of structurally related proteins, some of which have important biochemical and physiological functions other than RNA digestion.One homologue of pancreatic RNase that has an unusual ribonucleolytic activity is angiogenin (Shapiro et al., 1986b). This protein potently elicits neovascularization (Fett et al., 1985; Strydom et al., 1985), induccs second-messenger responses in cultured endothelial cells (Bicknell and Vallee, Con-rsyondeirce ro D. J. Strydom,

In vitro biological activity of bovine milk ribonuclease-4

“…Our results showed that the specificity of UpG was higher than that of CpG, confirming the nature of RNase-4. The singular specificity of this RNase has been reported to have a marked preference for uridine compared with cytidine, in contrast to the more general pyrimidine specificity of other ribonucleases such as rnase-1, -2, -3 and angiogenin (5). The kinetic constant obtained was lower than that reported in the literature for human and porcine rnase-4 (4).…”

“…it is a ubiquitous enzyme and is present in the highest amounts in the liver and lungs (4). a salient feature of rnase-4, which distinguishes it from other rnases, is its high interspecies similarity (90%), which strongly suggests that it performs a more specialized function than simply digesting or 'cleaning up' RNA (5). It was first isolated from bovine tissues in 1987, at which time it was called rnase Bl4 (6).…”

“…Bovine pancreatic ribonuclease-a (rnase-a) is the most frequently studied member of the rnase family, and has been used as a model to analyze protein structure and function (5,6).…”

An Angiogenic Protein from Bovine Serum and Milk — Purification and Primary Structure of Angiogenin‐2

“…Amino acid analyses were performed by the phenylisothiocyanate-precolumn-derivatization method (Bidlingmeyer et al, 1984) as described (Zhou and Strydom, 1993). Sequencing studies employed a Beckman 890 M sequencer .…”

Purification, identification and characterization of mammalian endoribonucleases that degrade c-myc mRNA in vitro.

“…When there is no activating stimulus present, the RNase L protein exists in a latent, catalytically inactive monomeric form and is bound by an inhibitory protein (RLI) (Bisbal et al 1995). However, upon binding 5'-triphosphorylated-2'-5'-A synthetase molecules, the protein forms a dimerized structure that activates the cytosolic endoribonucleolytic domain (Zhou et al 1993). In mammalian cells, activation of the RNase L protein leads to cell death via an apoptotic pathway (Pandey and Rath 2004).…”