Table Of Content10
Topics in Current Genetics
Series Editor:Stefan Hohmann
Sirkka Keränen • Jussi Jäntti (Eds.)
Regulatory Mechanisms
of Intracellular
Membrane Transport
With 23 Figures,7 of Them in Color;and 5 Tables
Dr.SIRKKAKERÄNEN
Dr.JUSSIJÄNTTI
VTT Biotechnology
Tietotie 2
P.O.Box 1500
Espoo
Finland 02044 VTT
The cover illustration depicts pseudohyphal filaments of the ascomycete Saccharomyces cerevisiae
that enable this organism to forage for nutrients.Pseudohyphal filaments were induced here in a wild-
type haploid MATa Σ1278b strain by an unknown readily diffusible factor provided by growth in con-
frontation with an isogenic petite yeast strain in a sealed petri dish for two weeks and photographed
at 100X magnification (provided by Xuewen Pan and Joseph Heitman).
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Table of contents
Introduction: Regulatory processes, an emerging feature in intracellular
membrane traffic...................................................................................................1
Sirkka Keränen and Jussi Jäntti.........................................................................1
Vesicle budding.............................................................................................3
Vesicle targeting – regulation by Rab GTPases............................................4
Tethering complexes.....................................................................................4
SM proteins...................................................................................................5
Regulation of SNARE assembly by protein phosphorylation.......................6
Phosphoinositides in membrane traffic.........................................................6
Regulation of de novo membrane formation.................................................6
References.....................................................................................................7
Molecular mechanisms in clathrin-mediated membrane budding....................9
Brigitte Ritter and Peter S. McPherson..............................................................9
Abstract.........................................................................................................9
1 Cellular sites of clathrin-mediated membrane budding..............................9
2 Formation of endocytic CCVs..................................................................10
3 Machinery for CCV formation at the cell surface....................................14
3.1 Role of clathrin.................................................................................14
3.2 Role of AP-2..........................................................................................15
3.3 Role of endocytic accessory proteins................................................18
3.4 Interactions of endocytic accessory proteins with AP-2...................23
4 Clathrin trafficking at the TGN................................................................26
4.1 AP-1 and GGA adaptor complexes...................................................26
4.2 Structural analysis of the (cid:74)-ear and GAE domain.............................28
4.3 Enthoprotin (Clint/epsinR): identification of a novel (cid:74)-ear/GAE
domain-binding consensus motif............................................................29
5 Concluding remarks.................................................................................30
Acknowledgments.......................................................................................31
References...................................................................................................31
Regulating membrane curvature.......................................................................39
Joost C. M. Holthuis........................................................................................39
Abstract.......................................................................................................39
1 Introduction..............................................................................................39
2 Topological considerations.......................................................................40
3 Extrinsic forces affecting membrane curvature........................................42
3.1 Cytoskeleton.....................................................................................42
3.2 Adhesion to curved particles.............................................................44
3.3 Coat assembly...................................................................................44
4 Intrinsic forces affecting membrane curvature.........................................46
VI Table of contents
4.1 Transbilayer area asymmetry............................................................46
4.2 Transbilayer curvature asymmetry...................................................52
4.3 Lipid domain-induced curvature.......................................................56
5 Concluding remarks.................................................................................57
Acknowledgements.....................................................................................57
References...................................................................................................58
Functions of Rab GTPases in organelle biogenesis..........................................65
Christopher G. Burd and Ruth N. Collins........................................................65
Abstract.......................................................................................................65
1 General considerations.............................................................................65
2 The GTPase cycle....................................................................................66
2.1 Structural features of Rab.................................................................68
2.2 Prenylation and localization of Rab GTPases...................................70
3 Regulation of inter-organelle trafficking and organelle transport............71
3.1 Cargo sorting and vesicle budding....................................................71
3.2 Regulation of membrane tethering and fusion..................................73
3.3 Rabs and membrane microdomains..................................................75
3.4 Organelle transport...........................................................................76
3.5 The roles of Rab GTPases in signaling pathways.............................77
4 Rab proteins in disease and development.................................................78
5 Perspective...............................................................................................78
Acknowledgements.....................................................................................80
References...................................................................................................80
Tethering proteins in membrane traffic............................................................89
Sarah Chu and Wei Guo..................................................................................89
Abstract.......................................................................................................89
1 Introduction..............................................................................................89
2 Tethering proteins in various traffic stages..............................................91
2.1 TRAPP..............................................................................................91
2.2 p115..................................................................................................93
2.3 Uso1p................................................................................................94
2.4 The COG complex............................................................................95
2.5 The exocyst.......................................................................................96
2.6 EEA1................................................................................................98
2.7 HOPS..............................................................................................100
2.8 The GARP/VFT complex...............................................................101
3 Postulated functions of the tethering proteins........................................102
4 Emerging common features of the tethering proteins............................103
5 Regulations of the tethering proteins......................................................105
6 Tethering proteins and sorting................................................................105
7 Future studies.........................................................................................106
Acknowledgment......................................................................................106
References.................................................................................................106
Table of contents VII
The function of Sec1/Munc18 proteins - Solution of the mystery
in sight?..............................................................................................................115
Maria Kauppi, Jussi Jäntti, and Vesa M. Olkkonen.......................................115
Abstract.....................................................................................................115
1 Introduction............................................................................................115
2 Genetic studies indicate an essential positive function for SM proteins in
vesicle transport.........................................................................................117
2 Genetic studies indicate an essential positive function for SM proteins in
vesicle transport.........................................................................................118
3 The structure of SM proteins..................................................................120
4 SM proteins display different binding modes to SNARE molecules.....121
5 Are the data suggesting an inhibitory role for SM proteins
physiologically relevant?...........................................................................123
6 At what stage of the vesicle tethering-docking-fusion process do SM
proteins exert their effects?.......................................................................125
7 Evidence for a role of SM proteins in transport and stability
of syntaxins...............................................................................................127
8 Protein phosphorylation regulates interactions of SM proteins with
syntaxins....................................................................................................128
9 Non-syntaxin interaction partners of SM proteins..................................129
9.1 Interactions of SM proteins with transport vesicle tethering
complexes.............................................................................................129
9.2 Interaction partners that regulate the SM protein-syntaxin
association.............................................................................................131
9.3 The Mint proteins............................................................................133
10 Do the SM proteins share a conserved function despite the different
modes of interaction with SNAREs?.........................................................134
Acknowledgements...................................................................................135
References.................................................................................................135
Regulation of SNARE assembly by protein phosphorylation........................145
Adina Weinberger and Jeffrey E. Gerst.........................................................145
Abstract.....................................................................................................145
1 Introduction............................................................................................145
2 Phosphorylation and control of the exocytic machinery........................147
2.1 Mammalian syntaxins.....................................................................147
2.2 Yeast syntaxins...............................................................................151
2.3 Arabidopsis syntaxin.......................................................................152
2.4 SNAP-25 and SNAP-23..................................................................152
2.5 VAMP/Synaptobrevins...................................................................155
2.6 SM Proteins....................................................................................155
2.7 Synaptotagmin................................................................................157
3 Protein phosphorylation in the endocytic pathway.................................158
3.1 Yeast Tlg1,2 and Vps45..................................................................158
3.2 VAMP4...........................................................................................159
3.3 Rabs 4 and 5....................................................................................159
VIII Table of contents
4 Protein phosphorylation in the early secretory pathway........................160
5 Conclusions............................................................................................161
Acknowledgments.....................................................................................162
References.................................................................................................162
Phosphoinositides and membrane traffic in health and disease....................171
Anna Godi, Antonella Di Campli, and Maria Antonietta De Matteis............171
Abstract.....................................................................................................171
1 PIs metabolism.......................................................................................171
2 The PI kinases: their subcellular localization and role in the secretory
pathway.....................................................................................................173
2.1 The PtdIns 3-kinases.......................................................................173
2.2 The PtdIns 4-kinases.......................................................................175
2.3 The PtdIns monophosphate kinases................................................177
3 The PI phosphatases: localization and function in the secretory
pathway.....................................................................................................179
3.1 The PI 3-phosphatases....................................................................179
3.2 The PI 4-phosphatases....................................................................181
3.3 The PI 5-phosphatases....................................................................181
4 PI metabolism and disease.....................................................................182
4.1 PTEN and human cancers...............................................................182
4.2 Myotubular myopathy and Charcot-Marie-Tooth disease..............183
4.3 Lowe syndrome..............................................................................184
5 Conclusions............................................................................................185
Acknowledgements...................................................................................185
References.................................................................................................185
Regulation of exocytotic events by centrosome-analogous structures..........193
Christof Taxis and Michael Knop..................................................................193
Abstract.....................................................................................................193
1 MTOCs: a brief overview......................................................................193
2 Spindle pole bodies and plasma membrane biogenesis in yeast
meiosis......................................................................................................195
2.1 PSM initiation.................................................................................196
2.2 Growth and shaping of the PSM.....................................................199
2.3 Closure of the PSM.........................................................................200
3 The IMC in Apicomplexa.......................................................................200
4 Centrioles, basal bodies and plasma membrane.....................................204
5 Conclusion.............................................................................................204
Acknowledgement.....................................................................................205
References.................................................................................................205
Index...................................................................................................................209
List of contributors
Burd, Christopher G.
Department of Cell and Developmental Biology, University of Pennsylvania
School of Medicine, 421 Curie Boulevard room 1010, Philadelphia, PA 19104-
6158, USA
[email protected]
Chu, Sarah
University of Pennsylvania, Department of Biology, Philadelphia, PA19104-
6018, USA
Collins, Ruth N.
Department of Molecular Medicine, C4-109, VMC, Cornell University, Ithaca
NY 14853-6401, USA
De Matteis, Maria Antonietta
Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Via
Nazionale, 66030 Santa Maria Imbaro (Chieti), Italy
[email protected]
Di Campli, Antonella
Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Via
Nazionale, 66030 Santa Maria Imbaro (Chieti), Italy
Gerst, Jeffrey E.
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot
76100, Israel
[email protected]
Godi, Anna
Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Via
Nazionale, 66030 Santa Maria Imbaro (Chieti), Italy
[email protected]
Guo, Wei
University of Pennsylvania, Department of Biology, Philadelphia, PA19104-
6018, USA
[email protected]
Holthuis, Joost C. M.
Department of Membrane Enzymology, Faculty of Chemistry, Padualaan 8,
3584 CH Utrecht, The Netherlands
[email protected]
X
Jantti, Jussi
VTT Biotechnology, Tietotie 2, Espoo, P.O. Box 1500, FIN-02044 VTT,
Finland
[email protected]
Kauppi, Maria
Department of Molecular Medicine, National Public Health Institute, Bio-
medicum, P.O.Box 104, FIN-00251, Helsinki, Finland
[email protected]
Keränen, Sirkka
VTT Biotechnology, Tietotie 2, Espoo, P.O. Box 1500, FIN-02044 VTT,
Finland
[email protected]
Knop, Michael
EMBL, Cell Biology and Biophysics Programme, Meyerhofstr. 1, 69117
Heidelberg
[email protected]
McPherson, Peter S.
Montreal Neurological Institute, McGill University, 3801 University, Mont-
real, QC, H3A 2B4 Canada
[email protected]
Olkkonen, Vesa M.
Department of Molecular Medicine, National Public Health Institute, Bio-
medicum, P.O.Box 104, FIN-00251, Helsinki, Finland
Ritter, Brigitte
Montreal Neurological Institute, McGill University, 3801 University, Mont-
real, QC, H3A 2B4 Canada
Taxis, Christof
EMBL, Cell Biology and Biophysics Programme, Meyerhofstr. 1, 69117
Heidelberg
Weinberger, Adina
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot
76100, Israel
Introduction: Regulatory processes, an emerging
feature in intracellular membrane traffic
Sirkka Keränen and Jussi Jäntti
The subject of this volume is the molecular mechanism of the intracellular mem-
brane trafficking, a central eukaryotic cell biological process. In the post genomic
era, essential molecules involved in intracellular membrane/protein transport are
emerging with increasing pace. The present challenge is to compile the molecular
networks that govern these processes. Understanding of regulatory processes and
participating molecules are likely to reveal global cellular regulatory circuits that
couple membrane trafficking with other cellular functions. The part of the mem-
brane transport machinery, which forms stabile protein complexes is rather well
known already. However, the regulatory mechanisms that link these more stabile
complexes to other cellular functions are only starting to emerge. This book fo-
cuses on the regulatory aspects of this process.
Continuous intracellular membrane traffic is needed for growth and mainte-
nance of the compartmental organisation of eukaryotic cells. This trafficking is
carried out by an elaborate and highly dynamic tubulo-vesicular network that en-
sures transport of membrane components, proteins, and lipids from their site of
synthesis to their site of function. The biosynthetic pathway, also called protein
secretion pathway and exocytotic pathway, leads from endoplasmic reticulum
(ER) to cell surface and to the endocytotic compartments via the Golgi complex
(Fig. 1). Proteins destined to plasma membrane and to the endocytotic compart-
ments as well as those secreted to cell exterior are first translocated to the ER. In
the ER, proteins undergo several types of posttranslational modifications and are
folded with the help of a number of chaperones and foldases. The properly folded
and oligomerised protein molecules are packaged into transport vehicles in
the form of membrane vesicles that are targeted to the next station, the Golgi
complex. Fusion of the vesicles with the Golgi membranes releases the proteins
into the Golgi lumen, where they may undergo further modifications. The trans-
Golgi network is the major sorting compartment in which the proteins are pack-
aged into vesicles that are targeted either to the plasma membrane or to the endo-
cytotic/lysosomal compartments. The endocytotic/lysosomal pathway is used to
transport material into the cell to the endosytic compartments and to lysosomes.
Basically, the same membrane transport mechanisms operate in all eukaryotic
cells from yeast to mammalian neurons and at the different transport steps within
the cell. Exocytosis of neurotransmitter-loaded transport vesicles bears striking
similarity with molecular mechanisms of transport vesicle fusion in other cell
types and even in unicellular eukaryotes like yeast. However, neurotransmitter
exocytosis of synaptic plasma membrane associated vesicles is evoked by plasma
membrane influx of calcium, which is triggered by membrane depolarisation. In
consequence, neuronal exocytosis involves calcium-binding synaptotagmin pro-
teins. For synaptotagmins homologues have not been identified, for example, in
Topics in Current Genetics, Vol. 10
S. Keränen, J. Jäntti (Eds.): Regulatory Mechanisms of Intracellular Membrane Transport
DOI 10.1007/b98736 / Published online: 16 June 2004
© Springer-Verlag Berlin Heidelberg 2004
