The ribosomal serine proteinase, cathepsin R. Occurrence in rat-liver ribosomes in a cryptic form.
Ribosomes have been shown to contain a proteolytic activity, characterized as an endopeptidase with serine in the active center. The enzyme has been given the name cathepsin R, following the recommendations of Barrett et al. (in a publication from the Cold Spring Harbor Laboratory, New York) for naming new proteinases. The present paper contains evidence that cathepsin R in rat liver ribosomes is present in a cryptic form. Upon dissociation of ribosomes to subunits (and to minor extent also by 0.5 M KC1 washes), the cryptic proteinase is released. Activation of the released cathepsin R is effected by equilibration with 2 M NaC1/0.05 M sodium acetate, pH 4.8. The molecular weight of free cathepsin R is 25 000-30 000.
D000818:Animals; D002403:Cathepsins / Q000302:isolation & purification*; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D007525:Isoelectric Focusing; D008099:Liver / Q000201:enzymology*; D008970:Molecular Weight; D051381:Rats; D012269:Ribosomal Proteins / Q000302:isolation & purification; D012270:Ribosomes / Q000201:enzymology*; D012697:Serine Endopeptidases
D012269:Ribosomal Proteins; C035145:ribosomal neutral proteinase; D002403:Cathepsins; D012697:Serine Endopeptidases