424 Unit 4 flash cards

In neurons, the synaptotagmin protein is localized to presynaptic axon terminals. When activated, it facilitates the fusion of neurotransmitter-containing synaptic vesicles to the plasma membrane, leading to neurotransmitter release into the synaptic cleft. Which of the following would you expect to directly activate synaptotagmin for this function? A. Ca++ B. Neurotransmitter C. Complexin D. Rab

A. Ca++

Where is calcium ion stored and how does it get into the cytoplasm to relay a signal? A. Ca++ is stored in the ER, it moves into the cytoplasm when gated calcium ion channels in the ER membrane open in response to a signal. B. Ca++ is stored in the nucleus, and is released by a nuclear localization signal C. Ca++is stored in the Golgi apparatus and gets into the cytoplasm through the Ca++ ATP pump. D. Ca++ is stored in the ER and is released by Calmodulin binding to calcium ion.

A. Ca++ is stored in the ER, it moves into the cytoplasm when gated calcium ion channels in the ER membrane open in response to a signal.

Misfolded proteins in the ER may actively undergo any of the following EXCEPT: A. Binding to chaperones to allow unfolding and refolding. B. Being expelled to the Golgi apparatus for disposal C. Binding to chaperones such to prevent aggregation. D. Being transported back to the cytosol for degradation.

B. Being expelled to the Golgi apparatus for disposal

Arrange the Following events in protein secretion in the proper sequence. 1. The polypeptide chain enters the lumen of the endoplasmic reticulum. 2. A Secretory vesicle is formed. 3. An ER transport vesicle is formed. 4. The polypeptide chain enters the lumen of the Golgi Apparatus.

C. 1,3,4,2 √

Exocytosis is said to be 'regulated' when? A. vesicles from the ER travel to the cell surface. B. binding to a fusion protein must occur first. C. vesicles travel from the Golgi to the lysosomes. D. a signal is required to trigger membrane fusion

D. a signal is required to trigger membrane fusion

Neuronal calcium sensor proteins are a family with very few known interacting partners

F

Proteins destined for secretory vesicles (for regulated secretion) begin to aggregate in the lumen of the trans-Golgi network (TGN).

F

The lumen of secretory vesicles is generally less acidic than the lumen of the TGN from which they originate.

F

Priming of secretory vesicles is the process of making docked vesicles competent to fuse with the plasma membrane upon arrival of signal

T

For translocation of a protein into the ER to occur, the ER signal sequence needs to bind ( SRP / ribosome / SRPT receptor / ribosome). This binding enables the complex to come to a translocator in the ER membrane and also causes translation to ( accelerate / slow down / pause / abort ) until docked at the membrane. The protein is then ( transported via vesicle, translated directly through translocator / unfolded and then refolded ) into the ER lumen.

SRP, pause, translated directly through translocator.

An ER membrane protein with two start/stop transfer signals, none of them at the N- terminal end, will be oriented with its C terminus in the cytoplasm

T

Exocytic vesicle components such as adaptors are recycled to the Golgi Apparatus in small clathrin-coated vesicles.

T