Biochemistry 3381A Study Guide - Quiz Guide: Phosphatidylinositol 4,5-Bisphosphate, Secretion, Clathrin

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27 May 2020

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Exocytosis outward from er to golgi and cell surface and endosomes: endocytic pathway. Plasma membrane to early endosome inwards from cell membrane late endosome: recycling and receptor sorting: retrieval pathway. Brings membrane and selected proteins back to compartment of origin. Clathrin composed of 3 larger smaller and 3 polypeptide chains triskelion (assemble to from coated pit) Has globular domain which binds to adaptor proteins. Cargo binds to receptor proteins which is a specific interaction. Adapter proteins (inner layer) come along and helps the clustering of the cargo, trap the cargo receptors and bind clathrin to the membrane. Clathrin (outer layer) molecule has a curved shape and interacts with the adaptor (specific interaction) Shaping of the membrane through these proteins which give the vesicle its form. Membrane binding proteins help bending and forming the vesicle have 2 domains: Pi(4,5)p2 binding site which binds proteins to the membrane + gtpase domain regulate the rate at which the vesicle pinches off from membrane.

Related Questions

Answer true or false for the following

a. NSF unwinds the v-SNARE/t-SNARE complex to allow membrane fusion during docking

b. Clathrin forms âcagesâ on vesicles that originate from plasma membrane.

c. Clathrin binds to adaptor proteins that link clathrin to membrane proteins.

d. Clathrin vesicles are used for endocytosis â bringing material across the plasma membrane and often delivering it to the early endosome

e. Clathrin mediates the fusion of the vesicles with early endosomes

f. Coated pits are formed from not wearing antiperspirant.

g. Rab (small GTPases) bound with GTP is critical for proper tethering of a vesicle/target organelle pair

h. Clathrin exhibits quaternary structure, defined by the assembly of three heavy chains and three light chains to form a triskelion

i. Compare to other filaments, only intermediate filaments have intrinsic ability to assembly and require no nucleation or assembly proteins

The vesicles that transport materials from donor membranes to acceptor membranes include:

	1.	COP-II coated vesicles
	2.	COP-III coated vesicles
	3.	COP-I coated vesicles
	4.	Clathrin coated vesicles

2.5 points

QUESTION 11

During skeletal muscle contraction, the roles of ATP include:

	1.	ATP is not required for forming the crossbridges between myosin and actin filaments.
	2.	ATP is utilized as a structural linker to mediate the interaction between myosin and actin filaments
	3.	Hydrolysis of ATP provides energy for myosin head to move along actin filaments and the binding of ATP to myosin head allows the detachment of myosin fromactin filaments.
	4.	ATP binds to actin filaments to drive the power stroke of myosin head.

2.5 points

QUESTION 12

One of the functions of smooth endoplasmic reticulum is

	1.	Synthesizing steroid hormone in the endocrine cells of the gonad and adrenal cortex
	2.	Serves as the starting point of the biosynthetic pathway
	3.	Synthesizing secretory proteins
	4.	Degrading cell debris

2.5 points

QUESTION 13

The function of COP-II coated vesicles is mainly:

	1.	Transporting materials from endosomes to Golgi complex
	2.	Moving materials from the ER to the ERGIC and Golgi complex.
	3.	Transporting materials from Golgi complex back to endoplasmic reticulum.
	4.	Involved in receptor-mediated endocytosis.

2.5 points

QUESTION 14

Which of the following processes is completed in rough endoplasmic reticulum?

	1.	Chaperones help misfolded proteins fold correctly.
	2.	Proteins that target to nucleus are synthesized in rough endoplasmic reticulum.
	3.	O-linked glycosylation occurs in rough endoplasmic reticulum.
	4.	Misfolded proteins are destructed in rough endoplamic reticulum.

2.5 points

QUESTION 15

Kinesin is the motor protein that coorporates with microtubules. It has the following functions:

	1.	It uses GTP as energy source.
	2.	It can hydrolyze ATP and use the energy to drive cargo along microtubules from minus end to plus end.
	3.	It has a globular head that can act as GTPase
	4.	The tail of kinesin is more diverse and binds to cargo

2.5 points

QUESTION 16

For correct segregation and trafficking, lysosomal proteins are tagged in the cis-Golgi with phosphorylated mannose residues, and then the tagged lysosomal enzymes are recruited to clathrin coated vesicles by mannose 6-phosphate receptors.

True

False

2.5 points

QUESTION 17

The process that specialized cells, such macrophages, engulf relatively large particles is:

	1.	Called pinocytosis
	2.	Called phagocytosis
	3.	Mediated by COP-II coated vesicles
	4.	Called autophagy

2.5 points

QUESTION 18

Proteins synthesized on rough endoplasmic reticulum and smooth endoplasmic reticulum are imported co-translationally to their destinations

True

False

2.5 points

QUESTION 19

Treatment of cells with a drug that promotes microtubule disassembly disperses Golgi complex into separate stacks of membrane compartments, suggesting that:

	1.	Golgi complex is made of microtubules.
	2.	Microtubules are important for the organization of Golgi complex.
	3.	Microtubules are transported into Golgi complex
	4.	Golgi complex is composed of tubulin proteins

2.5 points

QUESTION 20

Which of the following is correct about signal sequence of a secretory protein?

	1.	It is an âaddress codesâ for protein trafficking pathways
	2.	It is usually located at the C-terminus.
	3.	It targets the ribosome and the protein that is being synthesized to endoplasmic reticulum.
	4.	It is removed in Golgi complex.

apricotgrasshopper117

1/What is the fate of a protein with no N-terminus Signal Sequence?

(a)Transport through the constitutive secretory pathway

(b)Dispersal throughout the cytoplasm

(c)Transport into the nucleus

(d)Transport to the rough endoplasmic reticulum (RER)

2/ In nerve cells, Botulinum toxin-A degrades a subunit of a T-snare localized on the plasma membrane, how would this affect vesicular trafficking?

(a) It blocks the co-translational import of neurotransmitter proteins into the Endoplasmic reticulum via the translocon.

(b) It prevents the addition of carbohydrates to translated proteins

(c)It blocks the fusion of neurotransmitter-containing vesicles with the plasma membrane because theT-snare would not be able tophysically interact with the V-snare.

(d) None of the above

What is the correct order of events of Clathrin-mediated endocytosis?

1. Uncoating of Clathrin- coated vesicle

2. Recruitment of Clathrin and selection of cargo

3. Fusion of vesicle with early endosome

(a) 1, 2, 3

(b) 2, 1, 3

(d) 3, 1, 2

4/ Vesicles traveling anterogradely will eventually fuse with the cell membrane.

Which of the following elements does NOT participate in the fusion event?

(a) v-snare

(b) t-snare

(d) clathrin coat protein

When a cell releases a hormone into the bloodstream and a number of cells in a

distal location respond, this type of signaling is...

(a) Autocrine signaling

(b) Endocrine signaling

(d) Juxtacrine signaling

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Biochemistry 3381A Study Guide - Quiz Guide: Phosphatidylinositol 4,5-Bisphosphate, Secretion, Clathrin

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