what is meant by "endogenous parkin" and "endogenous ubiquitin" , i know what is parkin and ubiquitin but what is meant by endogenous here ?
It depens onan ubiquitin is conjugated with endogenous protein substrates or exogenous. It is possible because ubiquitin introduced this highly conserved protein as a molecule with extracellular actions or important intracellular functions. The same meanings are for a parkin protein which is E3-ubiquitin ligase. It is one of a number of proteins that ubiquitinate the substrate and mark them for degradation by the proteosome.