A genetic mutation occurs that alters the specificity of theGolgi enzyme that ph

Question

A genetic mutation occurs that alters the specificity of theGolgi enzyme that phosphorylates mannose residues in theoligosaccharides of glycoproteins. The effect of the mutation issuch that the enzyme now indiscriminately and randomlyphosphorylates mannose residues on all glycoproteins passingthrough the Golgi complex.

     A. What is the normal role ofthis enzyme?

       B. What is the normaldestination of Golgi contents that are phosphorylated on mannoseresidues and how do they get there?

      C. What are the consequences ofthis mutation?

Explanation / Answer

B. The Golgi apparatus adds a mannose-6-phosphate labelto proteins destined for lysosomes.Vesicles that leave the roughendoplasmic reticulum are transported tothe cis face of the Golgi apparatus, where theyfuse with the Golgi membrane and empty their contents intothe lumen.Once inside they are modified, sorted and shipped towards theirfinal destination (www.wikipedia.com).
C. Because of this mutation theenzyme has lost its specificity and will now randomly phosphorylatemannose residues on all glycoproteins necessary for the cell. Therewill be a loss of function of these proteins which may effectthings like formation of connective tissues such as collagen, or ifthey serve as receptors on cell surfaces, they will no longerbe able to bring other cells and proteins (collagen) togethergiving strength and support to a matrix.
Hope this helps.... B. The Golgi apparatus adds a mannose-6-phosphate labelto proteins destined for lysosomes.Vesicles that leave the roughendoplasmic reticulum are transported tothe cis face of the Golgi apparatus, where theyfuse with the Golgi membrane and empty their contents intothe lumen.Once inside they are modified, sorted and shipped towards theirfinal destination (www.wikipedia.com).
C. Because of this mutation theenzyme has lost its specificity and will now randomly phosphorylatemannose residues on all glycoproteins necessary for the cell. Therewill be a loss of function of these proteins which may effectthings like formation of connective tissues such as collagen, or ifthey serve as receptors on cell surfaces, they will no longerbe able to bring other cells and proteins (collagen) togethergiving strength and support to a matrix.
Hope this helps....

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