Biosynthesis of Glycoprotein in Neoplastic and Transformed Cells

Puromycin inhibits C-leucine incorporation into the proteins of Ehrlich cells but has relatively little effect on the incorporation of C-glu-cosamine into membrane-bound glycoprotein (Cook et al, 1965 Molnar et al., 1965b) this indicates the presence of a large reservoir of partially glycosylated glycoprotein molecules which can accept carbohydrate in the absence of new protein synthesis. 

Eylar and Cook (1965) reported the incorporation of C-galactose from UDP- C-galactose into endogenous protein acceptors by subcellu- 

These findings (Eylar and Cook, 1965 Caccam and Eylar, 1970 Molnar et al., 1969c) indicate that galactosyl transfer occurs predominantly on a smooth-surfaced fraction distinct from smooth endoplasmic reticulum the identity of this fraction as either Golgi apparatus or plasma membrane remains to be established. Hexosamine and mannose incorporation, however, probably occurs on both rough and smooth membranes. This pattern of sugar incorporation is similar to that described for liver and other tissues (see previous sections). 

HeLa cells can be fractionated into a rough-surfaced microsome fraction, a soluble fraction, and two distinct smooth-surfaced membrane fractions (Bosmaim et al., 1968a). One of these smooth fractions is enriched in 5 -nucleotidase and has the electron microscopic and chemical properties characteristic of plasma membrane the identity of the other smooth fraction has not been established and it is referred to as the smooth internal membrane fraction. It has been suggested by Bosmann et al. (1968a) that the smooth internal membranes may represent Golgi apparatus elements, but there is no evidence to substantiate this hypothesis. 

These results with intact HeLa cells indicate that little carbohydrate is 

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