The Effects of Spermine on the Ribonucleoprotein 

 Particles of Guinea-Pig Pancreas* 



Philip Siekevitz 

 The Rockefeller Institute, NezvYork, U.S.A. 



Introduction 



Our laboratory has been interested in the RNPf particles of the 

 pancreas for the past few years [1-7]. Particularly pure preparations of 

 these particles can now be obtained, having a diameter of 150 A [i, 6, 7]. 

 These particles have an RNA content of from 35 to 45",, [i, 7], a sedimen- 

 tation coefficient of 85 S [7] and a molar amount of Mg + + equivalent to 

 about one tenth that of the phosphate groups in the RNA [7]. The particles 

 as isolated have bound amylase, RNase and TAPase activities [6, 7]. 

 Indeed, after the injection of radioactive leucine, the chymotrypsinogen 

 which can be isolated from these particles has a higher specific radio- 

 activity, at the early time points after injection, than the chymotrypsinogen 

 isolated from other parts of the cell [6]. This finding indicates that these 

 particles synthesize chymotrypsinogen, and possibly other secretory 

 enzymes of the pancreas. 



When the Mg + + of the particles is removed by chelating agents such 

 as versene, ATP, GTP, and P-P, all of the above-named enzymes are 

 concomitantly removed together without about 25^0 of the total protein 

 and about 80",, of the RNA of the particles [7]. It was calculated [7] that 

 a good deal of the protein removed was made up of these bound enzymes. 

 The particles are still recognizable as such, but their diameter has been 

 increased about twofold [7]. We believe that the proteins synthesized on 

 the particles are there for a finite period of time and have to be removed 

 to complete the process of soluble protein synthesis. We were therefore 

 interested in finding conditions under which only the enzymes are released 



* This work was made possible by grant (A- 1635) from the National Institute 

 of Arthritis and Metabolic Diseases, National Institutes of Health, U.S. Public 

 Health Service. 



t Abbreviations used are: RNA, ribonucleic acid; RNA-P, ribonucleic acid 

 phosphate ; RNP, ribonucleoprotein ; P-P, inorganic pyrophosphate ; ATP and 

 GTP, adenosine and guanosine triphosphates ; tris, tris (hydroxymethyl) amino- 

 methane; RNase, ribonuclease ; TAPase, trypsin-activateable proteolytic activity; 

 TCA, trichloracetic acid. 



