Question

Insulin is a protein hormone that is secreted into the bloodstream when blood sugar is high. Imagine that insulin could be introduced into many different environments within and outside of cells. In which of the following environments would you expect insulin to be properly folded? (select all that apply)1. phagolysosomal lumen2. mitochondrial matrix3. extracellular space4. golgi lumen5. ER lumen6. cytosol

Answer 1

3. Extracellular Space: Insulin is in the bloodstream and breaks down compounds such as sugar. This protein would not be found inside any cell

Answer 2

In cells such as beta cells where insulin can be synthesized, properly folded insulin can be found in the cytosol in insulin secretary vesicles where they are stored until released thru beta cell detection of high blood glucose levels. In other cells, insulin is a extracellular ligand which does not enter the cell hence is also found in the extracellular space. The answer is thus 3 and 6.