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75 Rac1 interaction with CaM. Importance of the activation state, the plasma membrane localization and the cterminal polybasic domain Maite Vidal-Quadras 1 , Mariona Gelabert 1 , Anna Lladó 1 , Francesc Tebar 1 . Universidad de Barcelona, Spain, Casanova 143, 08036 1 Abstract: The small GTPase Rac1 regulates different cellular processes like migration, intracellular trafficking or phagocytosis by activating actin polymerization. Rac1 switches between an active GTP-bound form and an inactive GDP-bound form. In the active form, Rac1 interacts with their effectors, including activators of the Arp2/3 complex, and induces actin polymerization at particular cellular sites. It has been described that calmodulin (CaM) interacts with several small GTPases and therefore regulates cellular signalling and actin cytoskeleton. For instance, It has been already demonstrated that CaM binds to the hypothetical amphypatic alpha-helix of Rac1, corresponding to amino acids:151-164, and this interaction could regulate its activity (Elsaraj SM and Bhullar RP, BBA 2008). In this study, we have also demonstrated, in COS-1 cells, that endogenous Rac1 interacts with CaM in a calcium dependent manner. In addition, a direct binding between both proteins was also demonstrated by GST-sepharose4B affinity chromatography using purified proteins. Moreover, the binding kinetics between GST-Rac1 and CaM were analyzed by in vitro surface plasmon resonance technology (Biacore T-100, BioRad). The GST-Rac1 exhibited a high affinity for CaM (KD = 173 nM). These results demonstrated a high affinity and direct binding between Rac1 and CaM. Furthermore, we have uncovered new additional binding sites for CaM. Pull down CaM-sepharose, expression of different Rac1 mutants and immunoprecipitation experiments have revealed that activation state, membrane localization and the polybasic domain in the c-terminal of Rac1 are also necessary for CaM interaction. Interestingly, the c-terminal region of Rac1 is important for interaction with its effectors. We have discussed that association of CaM to this region may regulate Rac signalling.
76 A structural analysis of the ER in budding yeast by highresolution EM reveals how multiple ER domains are organized by membrane shaping proteins Gia Voeltz 1 . University of Colorado, Boulder 1 Abstract: We have used electron microscopy and tomography of cryofixed cells to visualize at nanometer resolution the structural and spatial organization of yeast ER. These data allow the major domains of the ER to be characterized in fine detail. The peripheral ER in the mother cell consists of three continuous though structurally distinct domains that include the plasma membrane associated ER, central cisternal ER, and tubular ER. We show that these interconnected domains vary in location, shape, volume to surface area ratios, and ribosome density. We have compared the properties and organization of ER domains at high resolution during six sequential stages of ER budding to reveal a vivid picture of ER domain organization and inheritance. We then examined the ER structure in a yeast strain lacking the membraneshaping proteins, reticulons and Yop1 to measure their contribution to ER domain organization. These data demonstrate that these membrane-shaping proteins regulate the dimensions, volume to surface area ratios, and ribosome density of all peripheral ER domains.
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October 28 - October 31, 2010 Bioch
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Symposium Agenda Thursday, October
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12:10 p.m. - 4:00 p.m. Lunch and Fr
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4:50 p.m. - 5:00 p.m. Discussion 5:
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Poster Presentations Last Names A -
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The Role of Ceroid Lipofuscinosis N
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A novel Golgi-localized protein inv
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2 The dynamics of SNARE complexes i
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4 Significant divergence in mammali
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6 The Tumoricidal Action of the Ade
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8 LMTK2 Regulates CFTR Recycling in
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10 Sorting in the Golgi Apparatus C
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12 Negative regulation of the endoc
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14 Mechanistic details of sorting n
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16 An ESCRTs View of Receptor Endoc
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18 GOLPH3 Bridges PtdIns(4)P and My
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20 Novel fluorescent probes to stud
Page 35 and 36: 22 Regulation of Ligand-Independent
Page 37 and 38: 24 A Fifth Adaptor Protein Complex
Page 39 and 40: 26 CATCHR-Family Tethering Complexe
Page 41 and 42: 28 Rab7 localization and activity a
Page 43 and 44: 30 The Drosophila Golgi transmembra
Page 45 and 46: 33 Cbl Amino Acids at a Putative Di
Page 47 and 48: 35 The role of COG subcomplexes in
Page 49 and 50: 37 Mechanism of secretory cargo sor
Page 51 and 52: 39 Understanding the mechanism of G
Page 53 and 54: 41 Mechanisms for selective activat
Page 55 and 56: 44 A novel coat complex traffics me
Page 57 and 58: 46 Membrane trafficking in cytokine
Page 59 and 60: 48 Phosphatidylinositol 4-phosphate
Page 61 and 62: 50 Control of Golgi function by Rab
Page 63 and 64: 52 Adenosine mediated modulation of
Page 65 and 66: 54 Syp1 regulation of actin polymer
Page 67 and 68: 56 Rap1A: A Novel Interactor Involv
Page 69 and 70: 58 Ctage5 is involved in the endopl
Page 71 and 72: 60 A vesicle carrier that mediates
Page 73 and 74: 62 Structural Insights into Dynamin
Page 75 and 76: 64 Identification and interaction m
Page 77 and 78: 66 hRME-6, a rab5GEF that integrate
Page 79 and 80: 68 Assembly of caveolin-1 and cavin
Page 81 and 82: 70 Opposing roles of Annexin A1 and
Page 83 and 84: 72 The role of SNX-BAR proteins in
Page 85: 74 TRAPP is required for ER exit of
Page 89 and 90: 78 Cell cycle-regulated Golgi stack
Page 91 and 92: 80 Rab 14 regulates tight junction
Page 93 and 94: 82 Dissecting the roles of O-glycos
Page 95 and 96: Author Index - A- Abay, S., 33 Acha
Page 97 and 98: Marsico, G., 83 Mattera, R., 11 Max
Page 99: 2011 ASBMB Special Symposia Series
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