Alterations of the posttranslational processing of a lysosomal enzyme in C6 XXXX cells.

@entity11 @entity10815 @entity6193 @entity14613
@entity10815 was assessed in C6 @entity11 cells grown in medium with an intermediate- or low-percent composition of serum. The amount, form, and subcellular location of @entity10815 differed after treatment with @entity14613 or @entity6193 in cells grown in a low-serum, growth-factor-supplemented medium. Immunoblotting showed that @entity10815 in the lysosomal fraction of the C6 cell line had a molecular weight (Mr) of 42 kD, whereas that in the microsomal fraction had Mr's of 42, 47, and 78 kD. After treatment for 1 to 16 hr with 4 mmol/L @entity14613 and subcellular fractionation, the molecular weight of lysosomal @entity10815 was the same in treated and untreated cells, but more enzyme was found in lysosomes of treated cells at 8 and 16 hr. In the microsomal fraction, the amounts of both the 42 and 47 kD forms were increased after 1 to 16 hr of treatment. When exposed to 20 mmol/L @entity14613 , C6 cells remained viable, but compared with untreated cells, they showed 25% less lysosomal @entity10815 , with increased amounts found in the microsomal fraction. The 78 kD protein detected by immunoblotting was present in both the lysosomal and microsomal fractions but was predominant in the latter. The apparent molecular weight of this protein was the same after @entity14613 but differed with @entity6193 , where Mr's of 39, 42, and 73 kD were found. @entity6193 -treated cells had less lysosomal @entity10815 and relatively more microsomal enzyme. The differing molecular weights of @entity10815 from @entity14613 - and @entity6193 -treated cells suggest that their inhibitions occur at different processing loci in distal elements of the Golgi stacks. The differences in the pI of @entity10815 and the number of its forms from @entity14613 - and @entity6193 -treated cells are also consistent with interference in the late stages of glycoprotein maturation. In this paper we show that the amount, molecular form, and consequent intracellular location of @entity10815 in cells of the C6 line can be affected by agents that selectively disrupt stages in Golgi-related protein modification and transport.
