Molecular sorting is a highly complex process taking place in eukaryotic cells, in which specific cargo molecules are collected in vesicles and dispatched to appropriate destinations. The first fundamental step of sorting, vesicle formation, is possible through the aggregation, on the membrane, of cargo molecules and a number of different endocytic proteins. The formation of such aggregate promotes membrane bending, leading to the budding and the extraction of a vesicle enriched with the engulfed molecular components. Recently, a theoretical model of this process was proposed, where the following events are described: proteins arrive on a membrane region, diffuse and aggregate into localized enriched domains, that are ultimately extracted after reaching a characteristic size.