Localization of Transmembrane Proteins: Roles of cytoplasmic motifs and transmembrane domains

RODRIGO QUIROGA; HUGO J. F. MACCIONI

Puerto Madryn

Congreso; XLVI Reunión Anual SAIB; 2010

SAIB

Transmembrane (TM) proteins are directed to their target organelles through several mechanisms, of which two will be analyzed in this work: Interaction with protein coats through aminoacidic motifs present in cytoplasmic tails, determining subcellular localization, and organelle-specific properties of TM domains. Neither the universality nor the distribution of cytoplasmic motifs has been analyzed. We have built a database with proteins whose subcellular localization and TM topology is known, which allows us to evaluate the presence of different motifs in the cytoplasmic tails of transmembrane proteins that localize to the Endoplasmic Reticulum, Golgi apparatus or plasma membrane. This same dataset is being analyzed to determine if TM domains belonging to proteins with different subcellular localizations possess distinct asymmetrical distribution of certain amino acids among transmembrane faces, membrane bilayer leaflets and distance to TM borders. Differences in these distributions could determine distinct physicochemical interactions with different lipids that compose membranes, which in turn, could determine lateral diffusion and inclusion into certain types of vesicles. Preliminary results indicate that organelle-specific TM properties exist, and that redefinition of certain cytoplasmic motifs allows us to suggest a novel Golgi retention motif.