Summary: This gene encodes an ubiquitin-like protein (ubiquilin) that shares high degree of similarity with related products 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 thought to functionally link the ubiquitination machinery to the proteasome to affect in vivo protein degradation. This gene is specifically expressed in the testis, and proposed to regulate cell-cycle progression during spermatogenesis. [provided by RefSeq, Jul 2008],