Exocytosis

Question 1

Describe secretory action and types

Answer 1

TGN aggregates proteins to maximize sec action

1. Constituitive - constant in sec proteins and PM (to EC matrix)
2. Regulated - Packaged and taken to PM and released on signal to give burst. Common sig = Ca

Question 2

What are the common destinations of vesicles

Answer 2

1. Lysosome - M6P tag

2. PM with regulated (signal groups same proteins) and constructive pathways

Question 3

Describe Constructive release variances

Answer 3

1. Unpolarized - needs no directional signaling
2. Polarized (most) - protein contains signal for apical or basolateral release
   Apical destinations are dig enzymes/ mucus
   Basolateral are to basal lamina

Question 4

What is transcytosis and an example

Answer 4

Endo and exo across epithelium reliant on pH variances for binding affinity of receptor.
EX: Ig6 in breast milk

Question 5

Describe processing in secretory vesicles

Answer 5

Concentration of contents as it travels through cytoplasm there is a progressive size reduction. Therefore concentration increases and increase of acidity to activate enzymes and dissociate receptors

Question 6

Describe vesicular dockig

Answer 6

RAB (6 prot) used
RAB-GTP = bound to vesicle and functions to bring RAB effector = docking mechanism allowing v and t snares to be close and begin fusion
NSF/SNAPs fan out v and t snares to induce final fusion

Question 7

What the Neuronal snares and vesicales

Answer 7

V-snare = synaptobrevin T-snare = Syntaxin

Synaptotagins are Ca sensors which trigger interaction with t snares allowing NSF to work and induce fusion

Question 8

Describe action of Botulin toxin

Answer 8

cleaves synaptobrecin in vesicles with ACH therefore it cannot release at NMJ leading to flaccid paralysis

Question 9

Describe action of Tetanus

Answer 9

Cleaves synaptobrevin on GABA and Glycine vesicles (inhib NTs) leading to spastic paralysis