Final answer:
The most widely endorsed model for how proteins are exposed to enzymes in each stack of the Golgi is the vesicular transport model, in which proteins are transported in vesicles from the cis-Golgi to the trans-Golgi network, undergoing modifications along the way.
Step-by-step explanation:
The most widely endorsed model for how proteins pass through the Golgi and are exposed to enzymes carried in each stack is the model of vesicular transport. According to this model, proteins are transported from the cis-Golgi network to the trans-Golgi network in vesicles. These vesicles contain specific transport proteins and enzymes that mediate the modification of proteins as they move through the Golgi stack. The proteins may undergo various modifications, such as glycosylation or phosphorylation, which can determine their final destination within the cell.