Question

What studies revealed the path of secretory proteins through the cell using autoradiography

while the synthetic activities of cells were being examined?
A) metabolic assays
B) pulse-chase experiments
C) fusiform studies
D) precipitation experiments
E) SDS-PAGE

Answer 1

Option (B), Pulse-chase experiments helped in the study of the path of secretory proteins in the cell, leading to the formulation of the Signal Hypothesis and demonstrating the role of the RER in protein processing.

Step-by-step explanation:

The studies that revealed the path of secretory proteins through the cell using autoradiography while the synthetic activities of cells were being examined are known as pulse-chase experiments. These experiments involved incubating cells with a pulse of radioactive amino acids (to label newly synthesized proteins) and then chasing with non-radioactive amino acids.

This technique allowed researchers like Gunther Blobel to track the temporal journey of proteins through a cell and led to the formulation of the Signal Hypothesis. The Signal Hypothesis states that secretory proteins have a signal peptide that directs them to the endoplasmic reticulum, which is later removed by an enzyme to create the mature protein. Blobel's work demonstrated that the rough endoplasmic reticulum (RER) contains processing activity and is essential for the synthesis and processing of secretory proteins.