LUC7L is a widely expressed RNA-binding protein that plays a critical role in pre-mRNA splicing through its function as a component of the U1 small nuclear ribonucleoprotein (snRNP) complex 1. The protein is homologous to the yeast Luc7p subunit and is normally required for 5' splice site selection 1. LUC7L belongs to a family of three human paralogs (LUC7L, LUC7L2, and LUC7L3) that differentially regulate two major classes of 5' splice sites, with LUC7L enhancing splicing of "right-handed" splice sites that have stronger consensus matching on the intron side of the invariant GU dinucleotide 2. The protein contains zinc finger domains that are functionally important for splice site recognition, with the second zinc finger domain specifically involved in splice site selection and showing different ATPase requirements for release by Prp28 during the splicing process 3. Evolutionary analysis indicates that LUC7 protein regulation of splice sites is highly conserved across species, with the LUC7L subfamily having evolved before the animal-plant split 2. The gene is located at the centromeric boundary of the human alpha-globin domain on chromosome 16.3 and has been implicated in various disease contexts, including prostate cancer drug resistance through its involvement in RNA splicing pathways 4.