Session 1: Signaling across Membranes

The apoptosis intrinsic pathway occurs because:

• caspases are released from the mitochondria

• a death ligand binds to a death receptor

• execution signals (cyt-c,…) are released from the mitochondria

• Bcl2 family proteins degrades cellular proteins

The Bcl2 family proteins:

• interact exclusively through their soluble domains to control apoptosis

• antiapoptotic members (Bcl-xL, Bcl-2,…) interact with caspases to prevent cell death

• proapoptotic members (Bax, Bak,…) form heteromeric pores at the mitochondrial outer membrane to release large execution signals (cyt-c, SMAC,…)

• heteromeric interactions among the transmembrane domains of pro- and antiapoptotic members modulate apoptosis

To design an efficient Bcl-xL inhibitor:

• it is mandatory to have the structure of the transmembrane interactions as a starting point

• it is possible to computationally design inhibitors based only on the sequence of the C-terminal transmembrane domain

• only soluble regions are good targets for inhibitor design

• the designed sequences always work as predicted by the models

Which of the following information is incorrect?

• Internal membranes are exclusively found in eukaryotic cells

• Membranes are dynamic structures.

• Protein adhesion to membrane surfaces can result in membrane protection.

• Membrane repair can involve vesicle formation.

Mark the correct answer:

Bacterial members of the ESCRT-III superfamily ….

• remain monomeric in solution.

• form large β-barrel structures in solution.

• form large helical assemblies in solution.

• are always membrane-attached.

What is the main function of proteins belonging to the Dynamin superfamily?

• Binding to DNA in the nucleus

• Remodeling membranes

• Generating a transmembrane proton gradient in the respiratory chain

• Inactivation of reactive oxygen species (ROS)

How is low pH affecting enterovirus infection?

• lowering entry and therefore lowering infectivity

• allowing entry but blocking viruses in early endosomes 

• no effect on infectivity

• increasing infectivity

What methods would not be used to quantify virus proliferation in cells:

• qPCR of the viral RNA

• cytopathic effect evaluation by microscopy

• sucrose gradient sedimentation of viruses

• confocal microscopy to evaluate the amount of capsid proteins

What does virus uncoating mean?

• virus proliferation

• sorting capsid proteins for capsid assembly

• process where genome is released from the capsid

• virus binding on cell surface receptors