1.    FUS (
Fused-In-
Sarcoma) is a nuclear protein that regulates gene expression. In 2009, two publications in the journal Science reported that mutations in FUS that alter the amino acid sequence in its nuclear localization signal (NLS) cause the disease amyotrophic lateral sclerosis (ALS), most likely by interfering with normal FUS function. 
In the space below, compose a hypothesis for how these mutations might interfere with FUS function.