We are interested in understanding the mechanisms that govern the movement of membranes proteins on their way to Lysosomes for degradation. This process depends on a trafficking step in which proteins are sorted into vesicles that bud inward into the lumen of the endosome. We now know that the attachment of ubiquitin confers sorting into this degradative pathway and that ubiquitin itself carries sorting information that is recognized by “ubiquitin-sorting receptors”. Currently, we are discovering and characterizing these ubiquitin-sorting receptors and determining how they are regulated.  We are also studying how the function of these sorting receptors is integrated into the formation of inward budding vesicles themselves. Finally, we are studying how the ubiquitination machinery comprised of Ub-ligases and Ub-peptidases, interfaces with the sorting process.