In a study about a new disease in humans, you find an accumulation COPII coated vesicles in one person and in a different person with similar symptom, an accumulation of uncoated vesicles.

Question

1- explain a possible mutation (2 total) that would result in each cellular observation.

2- how is it possible that both mutation could result in a similar symptom?

Answer 1

Proteins are moved from the endoplasmic reticulum (ER) to the Golgi apparatus for additional processing and sorting by a mechanism known as CopII vesicle transfer. Defects in this mechanism can arise from mutations in genes encoding parts of the CopII vesicle transport system.

A COPII gene disruption prevents ER export, which leads to a buildup of cargo molecules in the ER as well as a shortage of them at their final destination. The latter sets off the ER's unfolded protein response.

These mutations can affect how CopII vesicles develop, budding, or fuse, impairing the transfer of proteins from the ER to the Golgi. Numerous cellular and physiological effects, such as errors in secretion, altered lipid metabolism, and developmental anomalies, may follow from this. Human disorders like skeletal dysplasia and chondrodysplasia can occasionally result from mutations in the CopII transport mechanism genes.

It is possible that both mutations could arise due to affecting different downstream effects. If this pathway requires steps A->B->C->D, any mutation affecting A, B, or C will not lead to the final transported product (D) to be transported from the ER.