The final destination for proteins that follow the constitutive secretory pathway from the TGN in an unpolarized cell is:

Correct answer: The cell surface (plasma membrane).

Explanation

The trans-Golgi network (TGN) is a major sorting hub. It diverts proteins with specific signals to lysosomes or regulated secretory vesicles. All other cargo without such signals enters the constitutive pathway, which operates continuously to deliver material to the cell surface.

Other questions

Question 1

Which family of coat-recruitment GTPases is responsible for the assembly of both COPI and clathrin coats at Golgi membranes?

Question 2

What is the primary function of the protein dynamin in the formation of clathrin-coated vesicles?

Question 3

In the context of receptor-mediated endocytosis, what is the fate of the Low-Density Lipoprotein (LDL) after it dissociates from its receptor in the low pH environment of the early endosome?

Question 4

What type of signal directs soluble ER resident proteins, like BiP, back to the ER from the Golgi apparatus?

Question 5

The ESCRT protein complexes are essential for which of the following topologically equivalent processes?

Question 6

Which condition is necessary for the KDEL receptor to bind tightly to its KDEL-containing ligand proteins?

Question 7

In the process of regulated secretion, what is the primary trigger that causes secretory vesicles to fuse with the plasma membrane and release their contents?

Question 8

According to the cisternal maturation model of Golgi transport, how are Golgi resident enzymes maintained in their correct cisternae?

Question 9

What is the typical diameter of a synaptic vesicle, a specialized class of tiny secretory vesicles found in nerve cells?

Question 10

In polarized epithelial cells, where are proteins linked to the lipid bilayer by a glycosylphosphatidylinositol (GPI) anchor predominantly found?

Question 11

What is the primary function of the coat protein complex retromer?

Question 12

During receptor-mediated endocytosis of the transferrin receptor, what causes the iron-free transferrin (apotransferrin) to dissociate from its receptor?

Question 13

What is the role of the NSF protein in membrane trafficking?

Question 14

In the condition known as I-cell disease, a defect in which enzyme leads to the mis-sorting of lysosomal hydrolases?

Question 15

Which statement accurately describes the function of caveolae?

Question 16

What is the approximate internal pH of a lysosome, which is required for the optimal activity of its acid hydrolases?

Question 17

The process where a cell engulfs parts of its own cytosol or entire organelles into a double-membraned structure for delivery to the lysosome is called:

Question 18

What is the function of tethering proteins in vesicle transport?

Question 19

Which statement accurately describes the default secretory pathway from the trans-Golgi network (TGN)?

Question 20

How much of its own volume of fluid does a macrophage ingest each hour through pinocytosis?

Question 21

What is the key structural feature of a clathrin molecule that allows it to form polyhedral cages?

Question 22

The adaptor protein AP2, which links clathrin to cargo receptors, undergoes a conformational change that exposes its cargo-binding sites upon interaction with which molecule in the plasma membrane?

Question 23

What is the name of the structures formed when ER-derived COPII-coated vesicles fuse with one another before reaching the Golgi apparatus?

Question 24

How does the process of autophagy differ from phagocytosis?

Question 26

Which protein is responsible for initiating the assembly of COPII coats on the ER membrane?

Question 27

What is transcytosis?

Question 28

Which of the following is a key feature of selective autophagy?

Question 29

What is the role of the proteins Pink1 and Parkin in mitophagy?

Question 30

What is the estimated net concentration increase of a secretory protein from its initial state in the ER to its final state in a mature secretory vesicle?

Question 31

What are the two primary functions of the protein coat on a transport vesicle?

Question 32

v-SNAREs and t-SNAREs are complementary sets of proteins that mediate membrane fusion. Where are they typically found?

Question 33

What is the primary purpose of the quality control mechanism in the ER that retains misfolded or incompletely assembled proteins?

Question 34

In the exocytosis of synaptic vesicles, what is the direct role of synaptotagmin?

Question 35

Proteolytic processing of secretory proteins, such as converting pro-hormones to active hormones, occurs primarily in which locations?

Question 36

The lumen of which of the following compartments is NOT topologically equivalent to the cell exterior?

Question 37

Which class of proteins do SNAREs belong to?

Question 38

What type of vesicle mediates the retrieval of escaped ER resident proteins from the vesicular tubular clusters and the Golgi?

Question 39

What happens to the Rab protein after vesicle fusion is complete?

Question 40

A newborn baby obtains antibodies from its mother's milk, which are transported across the epithelial cells of its gut into the bloodstream. This process is an example of:

Question 41

The degradation of an endocytosed signaling receptor like the EGF receptor is terminated when it is sequestered into which structures?

Question 42

How many different SNARE proteins are present in a typical animal cell?

Question 43

Which of the following describes the composition of a typical t-SNARE?

Question 44

What is the function of the Rab cascade, for example the conversion of a Rab5-domain to a Rab7-domain on an endosome?

Question 45

Which part of the Golgi apparatus is described as a collection of fused vesicular tubular clusters arriving from the ER?

Question 46

What type of chemical modification is used to target certain signaling receptors, like the EGF receptor, for degradation via the endocytic pathway?

Question 47

In the process of phagocytosis, what triggers a phagocyte to extend pseudopods to engulf a target particle?

Question 48

What is the primary role of the protein complexin at the synapse?

Question 49

How is the symmetrical distribution of phospholipids in the two leaflets of the ER membrane generated?

Question 50

What is the primary mechanism by which macromolecules are sequestered into biomolecular condensates?