Santer M, Ruebush T K, Van Brunt J, Oldmixon E, Hess R, Primakoff P, Palade P
J Bacteriol. 1968 Apr;95(4):1355-67. doi: 10.1128/jb.95.4.1355-1367.1968.
Antibodies prepared against proteins from 50S ribosomes of Escherichia coli also reacted with the supernatant proteins of a cell-free extract of E. coli which was ribosome-free. A reaction of immunological identity (Ouchterlony tests) was demonstrated for one of these supernatant proteins and one protein found in 50S ribosomes. Isotope experiments involving a shift from (14)C-leucine medium to (12)C-leucine medium showed that these proteins are not formed by breakdown of ribosomes during the preparation of cell-free extracts, but instead represent a pool of ribosome protein which is utilized during growth. In shift experiments from (14)C-leucine to (12)C-leucine medium, the kinetics of disappearance of labeled supernatant ribosome proteins (as measured by reaction with antibody) indicated that half the pool is depleted in 0.1 generation time at 37 C in glucose-salts medium. The pool was also depleted under conditions of amino acid starvation of a "relaxed" strain which accumulated "relaxed" particles. Most, if not all, of the protein present in "relaxed" particles was derived from the pool. The pool represented about 3 to 4% of the total soluble proteins in the ribosome-free supernatant fluid of an E. coli extract.
针对大肠杆菌50S核糖体蛋白制备的抗体，也能与大肠杆菌无核糖体的无细胞提取物的上清液蛋白发生反应。对其中一种上清液蛋白和一种在50S核糖体中发现的蛋白进行了免疫同一性反应（双相免疫扩散试验）。涉及从（14）C-亮氨酸培养基转换到（12）C-亮氨酸培养基的同位素实验表明，这些蛋白质并非在制备无细胞提取物过程中由核糖体分解形成，而是代表了一组在生长过程中被利用的核糖体蛋白。在从（14）C-亮氨酸到（12）C-亮氨酸培养基的转换实验中，标记的上清液核糖体蛋白消失的动力学（通过与抗体反应测量）表明，在37℃的葡萄糖盐培养基中，该蛋白库的一半在0.1代时间内被耗尽。在积累“松弛”颗粒的“松弛”菌株氨基酸饥饿条件下，该蛋白库也会被耗尽。“松弛”颗粒中存在的大部分（如果不是全部）蛋白质都来自该蛋白库。该蛋白库约占大肠杆菌提取物无核糖体上清液中总可溶性蛋白质的3%至4%。
