Publication: Tráfico a través del aparato de Golgi y extensión apical en Aspergillus nidulans
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2018-11-05
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Universidad Complutense de Madrid
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Abstract
La ruta secretora es un proceso celular por el que determinadas proteínas maduran postraduccionalmente y son enviadas a los endosomas, al exterior celular o distribuidas en la membrana plasmática. Esta ruta comienza con la entrada de las proteínas recién sintetizadas al retículo endoplasmático (RE), donde se pliegan y sufren modificaciones postraduccionales, como la N-glicosilación [1] o el anclaje a glicosil fosfatidilinositol (GPI) [2]. A continuación las proteínas (cargos) viajan desde el RE al aparato de Golgi en vesículas recubiertas por el complejo proteico COPII (coat protein complex-II) [3]. Los llamados factores de anclaje o tethering las acercan a las cisternas en formación y la fusión de las vesículas con las cisternas ocurre gracias a la función de proteínas SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor). En el Golgi las cadenas de N-oligosacáridos se modifican y extienden [4, 5]. El aparato de Golgi es un conjunto de cisternas que organizan el tráfico intracelular, cuya identidad y funciones subyacentes están controladas por GTPasas pequeñas de la familia Rab [6] y de la familia Arf / Sar [7, 8]. Estas enzimas se reclutan a la monocapa citosólica de las membranas del Golgi al cargarse con GTP y se inactivan y liberan de dicha monocapa al hidrolizar el GTP. Estos dos eventos de carga e hidrólisis están regulados por los factores intercambiadores de nucleótidos de guanina (GEF) y por las proteínas estimuladoras de la actividad GTPásica (GAP), respectivamente. Cada GTPasa recluta un conjunto de proteínas efectoras (factores de tethering, proteínas SNARE, proteínas de cubierta y proteínas GEFs y GAPs, entre otros) a través de los cuales se ejecutan diversas funciones. Después de pasar por las cisternas del Golgi temprano o cis-Golgi, el cargo llega al Golgi tardío o trans-Golgi (TGN)...
The secretory pathway is a cellular process that is used to package certain protein molecules that are synthesized inside of the cell and are shipped out of the cell, to the plasma membrane (PM) or to the endosomes. Initially, newly synthesized proteins enter the endoplasmic reticulum (ER) by a process known as translocation. In the ER, cargo proteins are properly folded and some of them undergo N-glycosylation [1] or acquire a covalently attached glycosylphosphatidylinositol (GPI) anchor [2]. Next, cargoes exit the ER in COPII (coat protein complex-II) vesicles bound for the Golgi apparatus [3]. The initial interaction of this vesicle with a nascent cisterna of the Golgi is mediated by tethering factors and membrane fusion is facilitated by SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins. Once in the Golgi the N-glycans bound to proteins are modified and extended [4, 5]. The Golgi complex consists of a network of compartments or cisternae that organize intracellular traffic. The identity and functions of these cisternae are determined by small GTPases; mainly members of the Rab [6] family or the Arf/Sar family [7, 8]. These enzymes are recruited to the cytosolic face of the Golgi membrane and thus activated upon GTP binding, and become soluble and inactive by hydrolysis of the GTP. GTP hydrolysis is stimulated by interaction with a GTPase-activating protein (GAP) whereas GDP to GTP exchange is stimulated by GTPase exchange factors (GEFs). Each GTPase recruits specific effectors to the Golgi apparatus, such as tethering factors, SNARE proteins, coat complexes and GEF or GAP proteins, each of them performing diverse functions...
The secretory pathway is a cellular process that is used to package certain protein molecules that are synthesized inside of the cell and are shipped out of the cell, to the plasma membrane (PM) or to the endosomes. Initially, newly synthesized proteins enter the endoplasmic reticulum (ER) by a process known as translocation. In the ER, cargo proteins are properly folded and some of them undergo N-glycosylation [1] or acquire a covalently attached glycosylphosphatidylinositol (GPI) anchor [2]. Next, cargoes exit the ER in COPII (coat protein complex-II) vesicles bound for the Golgi apparatus [3]. The initial interaction of this vesicle with a nascent cisterna of the Golgi is mediated by tethering factors and membrane fusion is facilitated by SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins. Once in the Golgi the N-glycans bound to proteins are modified and extended [4, 5]. The Golgi complex consists of a network of compartments or cisternae that organize intracellular traffic. The identity and functions of these cisternae are determined by small GTPases; mainly members of the Rab [6] family or the Arf/Sar family [7, 8]. These enzymes are recruited to the cytosolic face of the Golgi membrane and thus activated upon GTP binding, and become soluble and inactive by hydrolysis of the GTP. GTP hydrolysis is stimulated by interaction with a GTPase-activating protein (GAP) whereas GDP to GTP exchange is stimulated by GTPase exchange factors (GEFs). Each GTPase recruits specific effectors to the Golgi apparatus, such as tethering factors, SNARE proteins, coat complexes and GEF or GAP proteins, each of them performing diverse functions...
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Tesis de la Universidad Complutense de Madrid, Facultad de Farmacia, leída el 08/02/2018