golgi vesicles and traffic Flashcards
1
Q
HVC
A
- hijacks host lipid metabolism and remodels host membranes to envelope itself
- double membrane vesicles
2
Q
endomembrane system
A
- organelles are connected directly by membranes or indirectly by transfer of membrane segments
3
Q
nuclear envelope + endoplasmic reticulum
A
- lumen of perinuclear cisternae is in continuity with the RER lumen
- outer membrane is similar to the membrane of RER
- inner has a different composition
- 2 types of membrane invagination into nucleoplasm
- GFP lamin
4
Q
the endoplasmic reticulum
A
- extensive membrane network of cisternae and tubuli
- quantity of ER quickly varies upon cell activation
- smooth ER lacks ribosomes on surface: site for lipids (steroids) synthesis and detoxification
- RER: ribosomes stud the surface: site for protein synthesis: products transferred via vesicles
- ER in most eukaryotic cells sequesters Ca2+ from cytosol
5
Q
RER:how do ribosomes bind?
A
- ribosomes not a stable part: constantly being bound and released from the membrane
- ribosomes bind through a receptor called ribophorin when it begins synthesis a protein to be secreted
- protein glycosilation begins in the RER and is completed in golgi
- vesicles shuttle proteins between these two compartments
6
Q
RER hypertrophy and acinar cells
A
- a significant increase in its amount
- acinar cells of exocrine portion of pancreas are abundant in ER
- principal site of pancreatic juice production
- pancreatin and other digestive enzymes are produced in RER and stocked in secretory granules
7
Q
visualising the RER
A
- RER is basophilic
- HandE, Nissl stain, GFP labeled proteins, IF,
8
Q
smooth endoplasmic reticulum
A
- in mainly cells are scanty and often party smooth and partly rough
- prominent in cells that specialise in lipid metabolism (e.g. steroid hormone synthesis
- many other reaction occur in SER: Gierke’s disease
9
Q
hepatocytes and SER
A
- rich in SER
- principal site of production of lipoprotein particles
- SER contains enzymes that detoxify both lipid-soluble drugs and various harmful compounds produced by metabolism
10
Q
muscle cells and SER
A
- muscle fibers abundant is specialised SER: sarcoplasmic reticulum
- release and uptake of Ca2+
- Ca2+ storage in lumen is facilitated by high cc of Ca2+ binding proteins
11
Q
Von Gierke’s disease
A
- glycogen storage disease type 1
- accumulation of glycogen in cytoplasm
- clinical signs: inadequate blood glucose levels, enlargement of liver, damage to tissue from hyperuricemia, bleeding infections
- deficiency of glucose-6-phosphatase enzyme located of SER membrane impairs ability of liver to produce free glucose from glycogen
12
Q
free ribosomes
A
- in cytoplasm
- appear as 25 nm granules by TEM
- synthesise proteins that remain in cytosol
- form clusters called polyribosomes
13
Q
golgi apparatus localisation
A
-positioned near the centrosome based microtubule-organizing center
- subdivided into 3 functionally distinguished compartments
- CIS forming face: vesicles fusing facing RER : network of membranous tubules appearance
- cis cisterna, medial cisterna, trans cisterna
- Trans maturing face releasing vesicles
- two alternative models for flux through golgi complex
14
Q
golgi functions
A
- post-translatioal modifications and sorting of neo-synthesize proteins
- synthesis of polysaccharide molecules (proteoglycans, mucins) and lipids
- sorting and dispatching station for the products of RER
- most glycosylation reactions occur in golgi
- signal-mediated diversion to lysosomes
- signal-mediated diversion to secretory vesicles for regulated secretion
- constitutive secretion
- N-glycosilation starts w addition of an oligosaccharide to NH2 group of an asparagine side chain
15
Q
cells with a well-developed golgi
A
- secretory cells
- synthesizing large amount of membrane and membrane-associated proteins
16
Q
intracellular traffic
A
- multidirectional, based on vesicle trafficking
- endocytic and biosynthetic secretory pathways
- retrieval pathway: maintenance of selected components backflow
17
Q
vesicle traffic
A
- complex but not chaotic
- membrane-bound proteins facing the cytosol target vesicles to their destination
18
Q
vesicle budding
A
- coat assembly and cargo selection: specific receptor for cargo molecules
- cargo receptor and adaptin bind to clathrin
- vesicle formation: dynamin: clathrin coated vesicle
- uncoating: naked transport vesicle
18
Q
coating functions
A
- to gather proteins in specific membrane region where vesicle should bud ensuring selective cargo
- to add rigidity determining the shape and size of the vesicle
18
Q
coating proteins (COP)
A
- 3 types: clathrin, COP I, COP II,
- most of coated vesicles bud only from specific regions of a membrane
- coating is made up of a cage of proteins facing the cytosol
19
Q
clathrin-coated vesicles
A
- clathrin subunits form complexes called triskelion
- each of 3 heavy and 3 light chains
- basket like cage
- secretory and endocytic pathways
19
Q
vesicle fusion
A
- fusion process to the target membrane is regulated by the snare proteins
20
Q
COP-coated vesicles
A
- heptameric protein complex involved in inner cell trafficking
- COP I: retrograde pathway, transport
- COP II: anterograde, RER-golgi transport
21
Q
coating: regulation of secretory pathway
A
- constitutive pathway: molecules released from the TGN to the PM, mostly uncoated, guided by sorting signals to the membrane region
- regulated pathway: molecules released from TGN in clathrin coated vesicles and stored in cytoplasm as larger secretory granules, guided by specific signals (e.g. hormones) to make them fuse with PM
22
Q
cells w lots of vesicles
A
- secretory cells
- lining epithelia
- cuboidal cells of PCT epithelium
23
Q
endocytosis
A
- receptor mediated endocytosis (RME) = clathrin-mediated endocytosis
- simulated cells display large number of projections
- receptor-mediated entry of specific molecules (hormones, abs LDLs
- clathrin coated vesicles
24
Q
ways of fluid/molecule uptake
A
- RME
- pinocytosis
- phagocytosis
25
Q
phagocytosis
A
- ingestion of large particles
- bacteria
- into large phagosomes
- non specific but receptor mediated
- un-coated vesicles but actin-dependent
26
Q
pinocytosis
A
- constitutive uptake of fluids or small molecules
- uncoated vesicles
27
Q
endosomal compartments and the lysosomes
A
- pinocytic vesicles lose their clathrin coats and fuse with early endosomes
- early endosomes: system of vesicles and tubules located near the plasma membrane sorting out endocytic material
- if contents require degradation it will be transferred to a late endosome
28
Q
progressive acidification of the endosomal compartments
A
- early to late endosome mature into lysosome
- pH 6.2 to 4.7
29
Q
lysosomes
A
- acidic vesicles with digestive enzymes
- digest worn out organelles, food particles, engulfed viruses, bacteria
30
Q
cells having lots of endosomes
A
- immunity cells
31
Q
lysosomal exocytosis
A
- process leading to secretion of lysosomal content
- lysosome fusion with PM
- important mechanism of cellular clearance necessary to maintain cell fitness
32
Q
autophagic machinery
A
- also involved in unconventional protein secretion and autophagy-dependent secretion
- fundamental mechanisms for toxic protein disposal, immune signalling and pathogen surveillance
33
Q
cell communication
A
- vesicles budding blebbing
34
Q
exosomes
A
- derive from multi-vesicular bodies
- size, content, functional and source heterogenity
- release is physiologically modulated
35
Q
types of molecules on, in exosomes
A
- integrin: cell adhesion
- immunnimodulatory
- antigen presentation
MVB exosomes biogenesis - tetraspanins
- lipid anchors, surface proteoglycans
- membrane transport
- contanin proteins, RNA, DNA, amino acids, metabolites
36
Q
exosome functions
A
- regulation of gene transcription and translation
- survival and proliferation
- reproduction and development
- angiogenesis and wound healing
- waste management
- host-microbiome interaction and viral immunity
- metabolic reprogramming and regulation
- cellular migration and metastatic disease
- cellular differentiation and neoplasia
- apoptosis
- receptor-ligand signalling
- balance of immune response and regulation of central and peripheral immunity
37
Q
tumour-derived exosomes
A
- molecular and genetic messages from tumor cells to normal or other abnormal cells residing at close or distant sites.
-found in all body fluids
38
Q
hyper/distrophic mice: experimental design
A
- serum collection and EV isolation
- miRNA isolation and analysis
- identification or miRNA that promotes myogenesis
- production of EVs carrying that miRNAs
5.insert into dis/atrophic mice
39
Q
A
