The fruit fly (Drosophila melanogaster) is an organism that is well-known for its use as a model for genetics studies. D. melanogaster has four autosomal chromosomes but also an X and a Y chromosome. Among the autosomal chromosomes, the fourth chromosome is the smallest. This chromosome contains very few genes and consists mostly of heterochromatin. My research project is centered around the protein POF (Painting of Fourth). POF specifically binds to the fourth chromosome. The aim of the project is to identify proteins that interact with POF. By identifying binding partners of POF we can understand more of the mechanism behind the specific binding of POF to the fourth chromosome.