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Master program MOLECULAR AND CELLULAR LIFE SCIENCES Block 1: Intracellular membrane processes
11-10-2012: 9:00-10:45 (BBL205) The endo-lysosomal system
Judith Klumperman Department of Cell Biology UMC Utrecht The Netherlands
1
Klumperman group :
- Understand how genetic mutations lead to cellular disorganization and disease, with special emphasis on diseases related to the cellular digestive system, the endo-lysosomes
- Development of (electron) microscopy methods: immunoEM, tomography, correlative microscopy
2
Department of Cell Biology, UMC Utrecht
3
What is endocytosis and why is it important? Entries into the cell Composition of the endo-lysosomal system Transport between endosomal compartments Targeting of newly synthesized lysosomal proteins lysosome-related functions and disorders
The endo-lysosomal system
What do cells do? Cells move
Cells reproduce
Cells eat
Cells communicate
Cells die
Macrophage chasing a bacteria
Cells eat
Source: Alberts, Molecular Biology of the Cell
A bacteria that is eaten by a macrophage ends up in a lysosome
bacteria
Macrophage
7
endosomal structures
PM
nucleus
Lysosomes live electron microscopy
The endo-lysosomal system
Golgi
ER
endosome
endosomes/lysosomes
plasma membrane
ER
intracellular
extracellular environment
mitochondria
9
What is endocytosis and why is it important? Entries into the cell Composition of the endo-lysosomal system Transport between endosomal compartments Targeting of newly synthesized lysosomal proteins lysosome-related functions and disorders
The endo-lysosomal system
1. essential molecules: nutrients, hormones, growth factors
2. pathogens: viruses, bacteria
3. drugs, medicines
Essential small molecules - amino acids, sugars, ions - traverse the plasma membrane through protein pumps or channels
Uptake of macromolecules occurs via membrane-bound vesicles that form from the plasma membrane => endocytosis
Endocytosis: the main entrance into the cell
Entries into the cell
11
Pinocytosis
phagocytosis
process of engulfing solid particles by the cell membrane to form an internal phagosome: e.g. bacteria, dead cells, small particles.
major mechanism to remove pathogens and cell debris
Clathrin-mediated endocytosis
Plasma membrane
cyt cyt cyt cyt
Clathrin coat
Lumen transport vesicle
Endocytosed proteins & lipids
14
15
Clathrin-mediated endocytosis
Plasma membrane
cyt cyt cyt cyt
Clathrin coat
Lumen transport vesicle
Endocytosed proteins & lipids
14
15
cytosol
Outside the cell
Plas
ma
mem
bran
e
16
Formation of clathrin coats requires adaptor proteins
17
Adapted from: Braulke and Bonifacino, BBA, 2008
Adaptor complexes involved in clathrin-mediated vesicular transport
TGN-to-endosome endocytosis endosome-to-lysosome
basolateral? APP in neurons?
18
19
What is endocytosis and why is it important? Entries into the cell Composition of the endo-lysosomal system Transport between endosomal compartments Targeting of newly synthesized lysosomal proteins lysosome-related functions and disorders
The endosomal system
Pathways to the lysosome: endocytosis
21
phagophore
autolysosome
autophagosome
Lecture Reggiori
Pathways to the lysosome: Autophagy
Lysosomes can secrete their content
23
Lysosomes digest their content to small units that are released into the cytosol and used for de novo syntheses of proteins and lipids
MVB/
MVB = multivesicular body 24
The early endosomal pathway
Early endosome ultrastructure
Bi-layered clathrin coat
Recycling tubule
Inward budding vesicle
ILVs
25
Sachse et al., MBC 13, 2002
clathrin10
wt-Rab14-GFP
EE
N
P HepG2: Tf10
Recycling Tf/TfR are found in early endosome associated tubules but do not accumulate in the clathrin coat and do not enter intraluminal vesicles
ILVs
Recycling tubules
26
27
1. Binding Tf and iron (Fe) to TfR
2. Release ferritin in endosome
3. Recycling Tf and TfR
4. Export Fe into cytoplasm
Why is recycling important? Iron uptake via the TfR cycle
P
EE
EE
I: EGFR concentrates in the endosomal clathrin coat II: EGFR concentrates in the
Intraluminal vesicles
HeLa + 5 min epidermal growth factor (EGF): EGFR10
Lysosome-directed epidermal growth factor receptor accumulates in the endosomal clathrin coat before incorporation into intraluminal vesicles
28
29
Why is endosomal sorting important? EGFR signaling and downregulation
Sorting into the intraluminal vesicles of MVBs/late endosomes attenuates EGFR signaling
ESCRT components are identified as tumor suppressors
Adapted from: Tanaka et al., Cancer Science 2008 30
The endosome associated ESCRT complex
Early endosomes: sorting by retention
EGFR is retained in the clathrin coat by the ESCRT complex and incorporated into intraluminal vesicles
TfR is not retained in the coat and follows the constitutive pathway to the recycling endosomes
=> the morphology of the early endosome strongly reflects its function by a sub-division into specialized membrane domains
Sachse et al., MBC, 2004
MVB/
MVB = multivesicular body 32
The late endosomal pathway
MVB/
LE
LYS
Lysosome biogenesis
Maturation of endosomes is reflected by an increasing number of intraluminal vesicles
Figure 2 from Jatta Huotari and Ari Helenius The EMBO Journal online publication doi:10.1038/emboj.2011.286
The endosome/lysosome system
2011 European Molecular Biology Organization. 34
35
From: Prior and Luzio, BBA, 2009
Research lecture Casper Jonker
Figure 6 from Jatta Huotari and Ari Helenius The EMBO Journal online publication doi:10.1038/emboj.2011.286
2011 European Molecular Biology Organization.
Late endosome motility.
38
What is endocytosis and why is it important? Entries into the cell Composition of the endo-lysosomal system Transport between endosomal compartments Targeting of newly synthesized lysosomal proteins lysosome-related functions and disorders
The endosomal system
Endo-lysosomes are at the crossroad of the endocytic and biosynthetic pathways
LAMP-1
LAMP-2
From: Eskelinen et al., Trends in Cell Biology, 2003
LAMP-3/CD63
LIMP-2
V-type H+-ATPase
~25 lysosomal membrane proteins
Building a functional lysosome
cathepsins
Lysosomal proteins Soluble lysosomal hydrolases => degradation Integral lysosome associated membrane proteins (LAMPs) => structural integrity
Lysosome biogenesis: transport of lysosomal proteins
LAMP-1
LAMP-2
lysosome
cathepsins
Mannose 6-phosphate receptors (MPRs)
=> transport of soluble lysosomal enzymes
Soluble lysosomal hydrolases are transported by mannose 6-phosphate receptors (MPRs)
cathepsins
From: Braulke and Bonifacino, BBA, 2008
MPRs mediate the TGN to endosome transport of the majority of lysosomal (acid) hydrolases
Mannose 6-phosphate receptors (MPRs) are the primary receptors for transport of lysosomal hydrolases
There are more than 50 lysosomal hydrolases which are equipped with a mannose-6-phosphate tag that is recognized by MPRs
43
Mannose 6-phosphate receptor (MPR)-dependent transport of soluble lysosomal enzymes
44
?
TGN to endosome transport pathways of LAMPs are unknown, but
independent of MPRs
LAMP-1
LAMP-2
45
Research in Klumperman group
46
What is endocytosis and why is it important? Entries into the cell Composition of the endo-lysosomal system Transport between endosomal compartments Targeting of newly synthesized lysosomal proteins lysosome-related functions and disorders
The endosomal system
General lysosomal functions degradation of extra- & intracellular material => digestion (extra)
=> autophagy (intra)
Lysosomes are the degradative end stations of the endocytic pathway
Melanosomes Pigmentation
Azurophilic granules Defense
Cytolytic granules Defense
MHCIIcompartments Immunity
Weibel-Palade Bloodclotting
Lysosomes are also involved in storage and secretion
48
>50 distinct diseases are caused by a defect in lysosome functioning
Worldwide 1:5000 births have a lysosomal disorder
Common symptoms: neuropathologies, kidney malfunctioning, bone deformations, muscle diseases, general failure to thrive
For most lysosome related disorders there is no cure
Lysosome related disorders
49
Classes of genetic lysosomal disorders
lysosomal storage/metabolic: >45 pigmentation-bleeding
non-metabolic without a pigmentation defect
Human disorders due to a deficiency in lysosomal function
Secondary lysosomal defects cancer
50
LIPIDOSIS SULFATASE MULTIPLE DEFICIT (AUSTIN DISEASE) FABRY * FARBER GAUCHER * KRABBE LANDING LEUCODYSTROPHY METACHROMATIC NIEMANN-PICK * SANDHOFF SCHINDLER TAY-SACHS WOLMAN CHEDIAK-HIGASHI SYNDROM MUCOPOLYSACCHARIDE DISEASES HUNTER * HURLER * MAROTEAUX-LAMY MORQUIO SANFILIPPO SCHEIE SLY MPS IX ABNORMAL LYSOSOMAL TRANSPORT SALLA DISEASE (Sialic acid storage disease) CYSTINOSIS * DANON OLIGOSACCHARIDOSIS DISEASES AND GLYCOPROTEINOSIS DISEASES MUCOLIPIDOSIS TYPE II (I Cell) MUCOLIPIDOSIS TYPE III MUCOLIPIDOSIS TYPE IV ASPARTYLGLUCOSAMINURIA SIALIDOSIS GALACTOSIALIDOSIS FUCOSIDOSIS MANNOSIDOSIS PYCNODYSOSTOSIS GLYCOGEN STORAGE DISORDER SYNDROME TYPE II ( POMPE DISEASE) * CEROD LIPOFUSCINOSIS DISORDERS PAPILLON-LEFEVRES SYNDROME
Lysosomal storage disorders
51
Classes of genetic lysosomal disorders
lysosomal storage/metabolic: >45 pigmentation-bleeding
non-metabolic without a pigmentation defect
Human disorders due to a deficiency in lysosomal function
Secondary lysosomal defects cancer
52
I-cell disease/ mucolipidosis II (MLII)
GlcNAc-phosphotransferase
Mucolipidosis II (MLII)
or I-cell disease
X
X
GlcNAc phosphotransferase equips lysosomal hydrolases with a M6P-tag that
in the TGN is recognized by MPRs
An increasing number of disorders is attributed to a disease of the lysosomal system..
54
Mucolipidosis II (MLII) => growth deficiency, mental retardation,
swollen salivary glands, skeleton distortions
Cellular characteristics: abnormal vacuolization (inclusions) in cells of mesenchymal origin, especially fibroblasts
The most severely affected system is the skeleton
rare disorder: ~1 in 640,000 live births
MLII mouse model (Gelfman et al., 2007. Invest. Ophtalmol. Vis. Sci. 48, 5221-5228)
330531
N m
G
m I-cell B cell: MHCII10
Eline van Meel
Inclusion body
I-Cell B cells contain inclusion bodies, which are a hallmark of I-cell disease
57
Children afflicted with mucolipidosis II and III generally are short in stature and have distinctive facial features.
Bone
Osteoclasts are bone resorbing cells that secrete acid hydrolases
Multi nucleated
Resorption lacuna: extracellular lysosome
TGN
Bone
1. Direct secretion 2. Via secretory lysosomes
Possible ways of lysosomal hydrolase secretion by osteoclasts
TGN
Resorption lacuna: extracellular lysosome
60
61
What is endocytosis and why is it important? Entries into the cell Composition of the endo-lysosomal system Transport between endosomal compartments Targeting of newly synthesized lysosomal proteins lysosome-related functions and disorders
The endosomal system
Principles of vesicular transport
Vesicular transport occurs by formation of a transport vesicle from a donor compartment and fusion with target organelle 62
Coats, tethers, SNAREs, Rabs
1. Selection of cargo
2. Formation of a transport vesicle
3. Transport of vesicle towards target compartment
4. Fusion with target compartment
Principles of vesicular transport
Coats
establish the initial connection between a vesicle and its target membrane two structurally different groups; multisubunit tethering complexes large coiled-coil tethering proteins.
Tethering proteins
SNAREs
RABs
Stenmark, 2009
Figure 15-21 Essential Cell Biology ( Garland Science 2010)
Figure 2 from Jatta Huotari and Ari Helenius The EMBO Journal online publication doi:10.1038/emboj.2011.286
2011 European Molecular Biology Organization.
The endosome/lysosome system
Lecture_Klumpermann (part1a).pdfSlide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Slide Number 51Slide Number 52Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Slide Number 60Slide Number 61Vesicular transport occurs by formation of a transport vesicle from a donor compartment and fusion with target organelleSlide Number 63Slide Number 64Slide Number 65Slide Number 66Slide Number 67Slide Number 68Slide Number 69
Lecture_Klumpermann (part1b)Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Slide Number 51Slide Number 52Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Slide Number 60Slide Number 61Vesicular transport occurs by formation of a transport vesicle from a donor compartment and fusion with target organelleSlide Number 63Slide Number 64Slide Number 65Slide Number 66Slide Number 67Slide Number 68Slide Number 69
Lecture_Klumpermann (part1c)Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Slide Number 51Slide Number 52Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Slide Number 60Slide Number 61Vesicular transport occurs by formation of a transport vesicle from a donor compartment and fusion with target organelleSlide Number 63Slide Number 64Slide Number 65Slide Number 66Slide Number 67Slide Number 68Slide Number 69
Lecture_Klumpermann (part1d)Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Slide Number 51Slide Number 52Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Slide Number 60Slide Number 61Vesicular transport occurs by formation of a transport vesicle from a donor compartment and fusion with target organelleSlide Number 63Slide Number 64Slide Number 65Slide Number 66Slide Number 67Slide Number 68Slide Number 69
Lecture_Klumpermann (part2)Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Slide Number 51Slide Number 52Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Slide Number 60Slide Number 61Vesicular transport occurs by formation of a transport vesicle from a donor compartment and fusion with target organelleSlide Number 63Slide Number 64Slide Number 65Slide Number 66Slide Number 67Slide Number 68Slide Number 69
Lecture_Klumpermann (part3a)Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Slide Number 51Slide Number 52Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Slide Number 60Slide Number 61Vesicular transport occurs by formation of a transport vesicle from a donor compartment and fusion with target organelleSlide Number 63Slide Number 64Slide Number 65Slide Number 66Slide Number 67Slide Number 68Slide Number 69
Lecture_Klumpermann (part3b)Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Slide Number 51Slide Number 52Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Slide Number 60Slide Number 61Vesicular transport occurs by formation of a transport vesicle from a donor compartment and fusion with target organelleSlide Number 63Slide Number 64Slide Number 65Slide Number 66Slide Number 67Slide Number 68Slide Number 69
Lecture_Klumpermann (part3c)Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Slide Number 51Slide Number 52Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Slide Number 60Slide Number 61Vesicular transport occurs by formation of a transport vesicle from a donor compartment and fusion with target organelleSlide Number 63Slide Number 64Slide Number 65Slide Number 66Slide Number 67Slide Number 68Slide Number 69
Lecture_Klumpermann (part4)Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Slide Number 51Slide Number 52Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Slide Number 60Slide Number 61Vesicular transport occurs by formation of a transport vesicle from a donor compartment and fusion with target organelleSlide Number 63Slide Number 64Slide Number 65Slide Number 66Slide Number 67Slide Number 68Slide Number 69
Lecture_Klumpermann (part5)Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Slide Number 51Slide Number 52Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Slide Number 60Slide Number 61Vesicular transport occurs by formation of a transport vesicle from a donor compartment and fusion with target organelleSlide Number 63Slide Number 64Slide Number 65Slide Number 66Slide Number 67Slide Number 68Slide Number 69