Parkinson's disease-associated mutations in α-synuclein and UCH-L1 inhibit the unconventional secretion of UCH-L1

► UCH-L1 is secreted from cultured cells by an unconventional pathway. ► Parkinson's disease-associated mutation in UCH-L1 decreased the secretion of UCH-L1. ► Parkinson's disease-linked α-synuclein mutations decreased the secretion of UCH-L1. ► The sequence between L32 and L39 in UCH-L1 is involved in the secretion of UCH-L1. ► The hydrolase activity of UCH-L1 is not necessary for the secretion of UCH-L1.