Advanced Cell Quizzes Chapter 13 and `15

Through this process, the secretory pathway delivers newly synthesized proteins, carbohydrates, and lipids either to the plasma membrane or extracellular space.

exocytosis

Adaptor Proteins

• are a major coat component in clathrin-coated vesicles

• are positioned between the clathrin cage and the membrane

• trap various transmembrane proteins, including transmembrane receptors that capture soluble cargo molecules inside the cell

Which type of coated vesicles mediates transport from the plasma membrane?

Clathrin

Phosphoinositide's can undergo rapid cycles of phosphorylation and dephosphorylation …

at the 3’, 4’, and 5’ positions of their inositol sugar headgroups Whi

What protein plays a major role in the pinching-off of coated vesicles?

dynamin

This protein is a hexameric ATPase that uses the energy from ATP hydrolysis to catalyze the disassembly of paired v-SNARE and t-SNARE proteins following fusion of a transport vesicle with its target membrane

NSF (N-ethylmaleimide-sensitive factor)

These proteins catalyze the membrane fusion reactions in vesicle transport.

SNARE proteins

Coat-recruitment GTPases …

include Sar1 and Arf proteins, and are found in high concentrations in the cytosol in an inactive GDP-bound state

Rab Proteins …

play a major role in directing transport vesicles to the correct target membrane

True or False: All transport vesicles are spherical

False

The targets that lie at the end of signaling pathways are referred to as …

effector proteins

Which of the following would occur most slowly in response to and extracellular signal?

a change in gene expression and synthesis of new proteins

What would activate a GTP-binding protein?

exchange of bound GDP for GTP

This type of signaling occurs over long distances and involves hormones that are secreted into the bloodstream.

endocrine signaling

True or False: One of the most important classes of molecular switches consists of proteins that are activated and inactivated by phosphorylation.

True

What term describes a signaling system in which low concentrations of signal do not have much effect, but then the response rises steeply and continuously at intermediate stimulus levels?

sigmoidal

What is a way that a cell can increase the specificity of interactions between intracellular signaling molecules?

by localizing signaling molecules in the same part of the cell or within large protein complexes

What is an example of a secondary messenger?

cAMP and Ca+2