Biochemical studies on rat liver Golgi apparatus. III. Subfractionation of fragmented Golgi apparatus by counter-current distribution.
Vesicular fragments of Golgi apparatus, smooth- and rough-surfaced microsomes from rat liver are differently partitioned in aqueous polymer two-phase systems consisting of dextran, polyethylene glycol, and sodium phosphate buffer. At a given polymer concentration, the amount of material partitioned in the top phase increases in the following order: rough microsomes less than smooth microsomes less than Golgi fragments. Counter-current distribution of Golgi fragments in the system consisting of 6.8% (w/w) dextran T500 and 6.8% polyethylene glycol 4,000 results in the separation of the fragments into three fractions; i.e. Fractions I, II, and III. NADH- and NADPH-cytochrome c reductase activities are detected almost exclusively in Fraction I, whereas the activities of galactosyltransferase, acid phosphatase, 5'-nucleotidase, and thiamine pyrophosphatase are maximal in Fraction III and minimal in Fraction I. The distribution of these enzymes suggests that Fraction I is similar to, though not identical with, microsomes, Fraction III resembles plasma membrane and lysosomes, and Fraction II is between the two. It is concluded that NADH- and NADPH-cytochrome c reductases are localized in a restricted region of the Golgi structure and that intra-Golgi differentiation seems to proceed in a discontinuous manner.
D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D003377:Countercurrent Distribution; D003579:Cytochrome Reductases / Q000378:metabolism*; D005700:Galactosyltransferases / Q000378:metabolism; D006056:Golgi Apparatus / Q000032:analysis* / Q000201:enzymology; D008099:Liver / Q000648:ultrastructure; D008247:Lysosomes / Q000201:enzymology; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism*; D009708:Nucleotidases / Q000378:metabolism; D051381:Rats; D013834:Thiamine Pyrophosphatase / Q000378:metabolism
D003579:Cytochrome Reductases; D009251:NADPH-Ferrihemoprotein Reductase; D005700:Galactosyltransferases; D009708:Nucleotidases; D000135:Acid Phosphatase; D013834:Thiamine Pyrophosphatase