Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Ubiquilin-1 is a protein that in humans is encoded by the UBQLN1 gene. This gene encodes an ubiquitin-like protein (ubiquilin) that shares high degree of similarity with related proteins in yeast, rat and frog. Ubiquilins contain a N-terminal ubiquitin-like domain and a C-terminal ubiquitin-associated domain. They physically associate with both proteasomes and ubiquitin ligases, and thus are thought to functionally link the ubiquitination machinery to the proteasome to effect in vivo protein degradation. This ubiquilin has also been shown to modulate accumulation of presenilin proteins, and is found in lesions associated with Alzheimer''s and Parkinson''s disease. Two transcript variants encoding different isoforms have been found for this gene.