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Integrated G Proteins Signaling in Plants

:	Shaul Yalovsky, Frantisek Baluska, Alan Jones
:	Shaul Yalovsky, František Baluška, Alan Jones
:	Integrated G Proteins Signaling in Plants
:	Springer-Verlag
:	9783642035241
:	1
:	CHF 132.70
:

:	Mikrobiologie
:	English

:	336
:	Wasserzeichen/DRM
:	PC/MAC/eReader/Tablet
:	PDF

This volume focuses on the structure, function and regulation of plant signaling G proteins and their function in hormonal pathways, polarity, differentiation, morphogenesis and responses to biotic and abiotic stresses.

Plants are sessile organisms that need to continuously coordinate between external and internal cues. This coordination requires the existence of hubs to allow cross-talk between different signaling pathways. A single family of Rho GTPases, termed either ROPS or RACs, and heterotrimeric G proteins have emerged as the major molecular switches in a multitude of signal transduction pathway in plants.

	Preface	4
	Contents	8
	Plant Ga Structure and Properties	10
	1 Introduction: Structure–function Relationships in G Protein Signaling	11
	2 Comparison of Plant Ga Proteins to Mammalian Ga Proteins	12
	2.1 Switch Regions and the Gbg Interacting Interface	12
	2.2 Guanine Nucleotide-Binding Pocket	16
	2.3 Loop Insertions	17
	2.4 The a5 Helix	17
	2.5 RGS Interacting Interface	18
	2.6 Receptor and Effector Coupling	18
	2.7 Cholera Toxin and Pertussis Toxin	19
	2.8 Contacts Between Ras-like and Helical Domains ( Linkers 1 and 2)	19
	2.9 Other Residues of Interest: Tools for Studying G Protein Signaling	19
	2.10 Summary of Structural Comparison Between Plant and Mammalian Ga Proteins	20
	3 Properties of Plant Ga Proteins	20
	3.1 Kinetic Properties of the Arabidopsis Ga Protein	20
	3.2 Kinetic Properties of Other Plant Ga Proteins	21
	3.3 Possible Structural Determinants of Rapid Nucleotide Exchange	22
	3.4 Plant Ga Lipid Modification and Subcellular Localization	22
	3.5 Candidate Plant GPCRs	23
	3.6 Candidate Plant Ga Effectors	25
	3.7 Candidate Effectors in Plants Identified by Homology to Animal Effectors	27
	4 Conclusions: Plant Ga Proteins are like Animal Ga Proteins, but Different	28
	References	29
	Regulatory and Cellular Functions of Plant RhoGAPs and RhoGDIs	35
	1 Introduction	35
	2 RhoGAP Protein Families	37
	2.1 Plant RhoGAP SubFamily I: CRIB domain proteins	40
	2.2 Plant RhoGAP Subfamily II: PH Domain Proteins	45
	3 RhoGDI Protein Families	47
	3.1 AtROPGDI1: Maintenance of Cellular Polarity Required for Root Hair Initiation and Growth	49
	3.2 NtRhoGDI2: Maintenance of Polarized Rho GTPase Activation at the Tip of Tobacco Pollen Tubes	50
	4 Conclusions	52
	References	53
	Structure and Function of ROPs and their GEFs	57
	1 Introduction	57
	2 Structure and Function of ROPs	59
	2.1 Structural Characteristics of ROP Proteins	59
	2.2 Nucleotide Binding, GTPase Activity, and Commonly Used Mutants	62
		62
	62	62
	2.3 Plant- and Isoform-Specific Structural Features	63
	3 RopGEFs: Novel Activators for Rho Proteins in Plants	65
	3.1 Identification of RopGEFs	65
	3.2 Architecture of RopGEFs and Mode of Substrate Binding	66
	3.3 Insights into the Catalytic Mechanism of RopGEFs	67
	3.4 Substrate Specificity of RopGEFs	71
	3.5 RopGEFs in the Physiological Context	72
	4 Conclusions	73
	References	73
	Protein–Lipid Modifications and Targeting of ROP/ RAC and Heterotrimeric G Proteins	78
	1 Introduction	78
	2 The Lipid Modifications 2.1 Prenylation and CaaX Processing	80
	2.2 S-Acylation	82
	2.3 N-Myristoylation	84
	3 Lipid Modifications and Subcellular Targeting of ROPs 3.1 Subcellular Distribution and Function of ROPs	84
		84
	84	84
	3.2 Prenylation of Type-I ROPs	85
	3.3 Transient S-Acylation of Type-I ROPs	86
	3.4 Stable S-Acylation of Type-II ROPs	87
	3.5 Role of the Polybasic Domain for Plasma Membrane Targeting	88
	4 Plasma Membrane Microdomains 4.1 The Lipid Raft Hypothesis	90
	4.2 Accumulation of ROPs in Membrane Microdomains	90
	5 Lipid Modifications and RhoGDI	91
	6 Lipid Modifications and Targeting of Heterotrimeric G Proteins 6.1 Modification of the Ga and Function of Hetertrimeric G Protein in Plants	91
	6.2 Prenylation and S-Acylation of Gg Subunits	92
	7 Conclusions	93
	References	93
	ROP GTPases and the Cytoskeleton	98
	1 Introduction	98
	2 Regulation of AFs	99
	2.1 Conserved Rho GTPase Downstream Pathways in the Regulation of AFs	100
	2.2 Plant-Specific Players in the ROP-Dependent Regulation of AFs	102
	3 Regulation of Microtubules	104
	4 Crosstalk Between AFs, MTs, and ROPs	105
	5 Conclusion and Perspectives	106
	References	107
	RAC/ROP GTPases in the Regulation of Polarity and Polar Cell Growth*	112
	1 Introduction	113
	2 RAC/ROP, a Tip-Localized Regulator for the Polarized Pollen Tube Growth Process	114
	3 RAC/ROPs as Regulators for Root Hair Tip Growth	118
	4 RAC/ROPs as Regulators of Polarized Cellular Activity Associated with Differentiation, Development and Defense	121
	5 Insights from Upstream RAC/ROP Regulators on Their Role in Polarized Cell Growth	123<