<;()L(;l MEMBRANES 



121 



20 



40 60 20 40 



MINUTES OF CENTRIFU6ATI0N 



Fig. 6. Appearance of biochemical components in the Golgi fraction at various times of 



centrifugation. The arrangement for gradient fractionation was the same as that shown in 



figure 5. Centrifugation was at 35,600 rpm for the times indicated on the abscissa. Open squares 



denote hpid P: closed squares, aciil phosphatase; open circles, alkaline phosphatase; closed 

 circles, DPNH-cyto.c reductase; broken line, total N. 



ponents of which are in general smaller than those seen in figures 7 and 8. The 

 profiles of some of the individual large vesicles are indistinguishable from those 

 seen in association with the organized Golgi structures (or, it may be noted, from 

 the numerous smooth-surfaced vesicles seen in microsome fractions of epididymis 

 as well as liver (13)). This fraction may contain some Golgi material that had 

 been extensively comminuted during homogenization. As yet, we cannot identify 

 morphologically the elements with which the alkaline phosphatase activity was 

 associated. 



We thought it desirable to compare the biochemical properties of Golgi frac- 

 tions isolated by a relatively short centrifugation and consisting principally of 

 recognizable Golgi membranes, with the properties of other cytoplasmic ma- 

 terial. A mitochondrial and two microsomal fractions (fig. 10) were isolated 

 from epididymis by differential centrifugation in 0.88 m sucrose and washed in 

 sucrose containing 0.34 m sodium chloride. Golgi structures were very poorly 

 preserved in fractions isolated in the absence of added salt. Possibly some Golgi 

 material was present in the mitochondrial fraction; none was seen, even with the 

 electron microscope, in the microsomal fractions. Of the biochemical components 

 under consideration, only RNA was found to be preferentially extracted upon 

 washing with 0.34 m sodium chloride. Accordingly, the RNA values presented 

 in figure 10 were derived from fractions isolated either in sucrose-0.08 m sodium 



