Astrocytes are a non-neuronal cell population in the brain which perform many important functions, including regulating synapse formation and function and helping to form the blood brain barrier. Despite the importance of these cells in vivo, little is known about how they carry out these critical functions. Protein Tyrosine Phosphatase Receptor Z1 (PTPRZ1) is a transmembrane protein which is heavily expressed in astrocytes and oligodendrocytes, another non-neuronal cell in the brain. While some function has been found for PTPRZ1 in controlling oligodendrocyte maturation, little is known about the function of the protein in astrocytes. The present study investigates the role of this protein by determining its location of action, its expression across development, and finally what it is doing in astrocytes. To determine the location in which PTPRZ1 is acting, immunohistochemistry (IHC) was used on mouse brain sections. These tests showed expression of PTPRZ1 along the branches of astrocytes, with a co-localization between the PTPRZ1 and our astrocyte marker GFP. We also found the protein to be present on western blot in the brains of mature animals. We plan to continue this work by investigating PTPRZ1 levels over different developmental time-points using western blot and quantitative PCR analysis.