Module 9.1 - Apical vs Basolateral & Axonal vs Dendrite

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Questions and Answers

What is the key to the polarization of membranes?

Microtubule orientation and triton-insolubility

Selective endocytosis and retrograde motors

Differential staining and axonal hillock localization

Selective retention and vectorial sorting (correct)

What is the role of ankyrin-G in protein sorting?

Ankyrin-G mediates endocytosis from the axon

Association with ankyrin-G leads to trapping of protein at axonal hillock (correct)

Ankyrin-G is involved in dendritic targeting

Ankyrin-G is responsible for retrograde transport

What is sufficient for localization to the axon hillock?

Addition of the loop from the sodium channel (correct)

Endocytosis from cytoplasmic loop

Triton-insolubility

Association with ankyrin-G

What is required for endocytosis association but not for interaction with ankyrin-G?

One region (aa1010-1030) Signup and view all the answers

What is important in the differentiation of neuronal processes?

Microtubules Signup and view all the answers

What is targeted to dendrites?

Proteins with specific sorting signals Signup and view all the answers

What would be detrimental for dendritic targeting?

Selective endocytosis from axon Signup and view all the answers

What is enriched in axonal hillock?

Ankyrin-G Signup and view all the answers

What is sufficient for trapping of protein (triton-insolubility)?

Association with ankyrin-G Signup and view all the answers

What is required for full sorting to axonal hillock?

Two motifs, both required Signup and view all the answers

Which process is key to the polarization of membranes?

Vectorial sorting and selective retention Signup and view all the answers

What is the function of tight junctions in epithelial cells?

Prevent leakage through epithelial layer and diffusion of membrane Signup and view all the answers

What are the distinct environments faced by some cells?

Apical side faces the outside world; Basolateral side faces the inside world Signup and view all the answers

What is the role of microtubules in neuronal processes?

Important in differentiation of neuronal processes Signup and view all the answers

How are components of apical and basolateral membranes sorted?

Into distinct vesicles in the TGN or in endosomes Signup and view all the answers

What defines the interface between apical and basolateral sides of epithelial cells?

Tight junctions Signup and view all the answers

What must be distinctly targeted to maintain correct balance in cells?

Ion channels, transporters, and lipids Signup and view all the answers

What prevents leakage through the epithelial layer?

Tight junctions Signup and view all the answers

What guides the sorting of proteins to their appropriate destinations within cells?

Specific signals like tyrosine-based motifs and di-leucine motifs Signup and view all the answers

Which subunit plays a crucial role in sorting basolateral proteins with tyrosine-based motifs?

AP1B subunit Signup and view all the answers

What guides apical sorting in cells?

Signals like lipid linkage and glycosylation Signup and view all the answers

What is necessary and sufficient for determining the axon in neuronal polarity?

PI-3 kinase signaling Signup and view all the answers

What forms a diffusion barrier between the axon and soma, stabilizing the axon's polarity?

Ankyrin G and actin filaments at the axon hillock Signup and view all the answers

What is involved in axonal determination?

Rules such as the longest neurite becoming the axon and the involvement of motor proteins like kinesin Signup and view all the answers

What are neurons highly sensitive to in terms of transport vesicles?

Distinct V-SNAREs Signup and view all the answers

What plays crucial roles in axonal determination?

Dynamic microtubules and post-translational modifications of tubulins Signup and view all the answers

What is the role of specific isoforms of kinesin in neuronal polarity?

Transport vesicles down axons Signup and view all the answers

What is involved in the sorting of proteins to distinct cellular compartments?

Distinct transport mechanisms Signup and view all the answers

Study Notes

Intracellular Protein Sorting and Neuronal Polarity

Sorting of proteins within cells varies based on the type of protein and the cell it is in
Different proteins are directed to different cellular compartments, such as apical or basolateral, through distinct transport mechanisms
Specific signals, like tyrosine-based motifs and di-leucine motifs, guide the sorting of proteins to their appropriate destinations
AP1B subunit, found only in polarized cells, plays a crucial role in sorting basolateral proteins with tyrosine-based motifs
Apical sorting occurs through direct transport vesicles, endosomes, and transcytosis, guided by signals like lipid linkage and glycosylation
Neuronal polarity involves complex cellular organization, with axon and dendrite differentiation modifying apical and basal polarity
Axonal determination involves rules such as the longest neurite becoming the axon and the involvement of motor proteins like kinesin
Specific isoforms of kinesin transport vesicles down axons, and PI-3 kinase signaling is necessary and sufficient for determining the axon
Dynamic microtubules and post-translational modifications of tubulins play crucial roles in axonal determination
Ankyrin G and actin filaments at the axon hillock form a diffusion barrier between the axon and soma, stabilizing the axon's polarity
Different types of apical and basolateral transport vesicles are sensitive to distinct V-SNAREs, with tetanus toxin blocking basolateral transport, but not apical transport
Neurons have a high degree of polarity, with unique compartments such as axon hillock, pre-synaptic terminal, and dendrites, involved in information processing and transmission

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Test your knowledge of intracellular protein sorting and neuronal polarity with this quiz. Explore the mechanisms of protein sorting within cells and the complex organization of neuronal polarity, including axon and dendrite differentiation, transport mechanisms, and signaling pathways crucial for determining axonal polarity.