Cell combination

Fraction of label in pellet (protein with galactose)

Fraction of label in supernatant (protein without galactose)

Labeled wild-type cells fused with non-labeled wild- type cells

85% (this shows that wild type cells are working OK, galactose is being added to the labeled glycoprotein)

15%

Labeled mutant cells fused to non-labeled mutant cells

5% (no galactose is added)

95%

Labeled mutant cells fused with non-labeled wild-type cells

45%

(galactose is added to about 40% of the labeled molecules).

This means

• that wild-type enzyme was transferred via vesicle transport to the mutant Golgi, or
• that the labeled materialfrom mutant Golgi got into the non-labeled wild-type Golgi via vesicle transport
• the enzymes tht add galactose to the labeled protein had to come from come from wild type cells.

55%

Mutant proteins in the defective cells can not add galactose to the labeled protein.