The plasma membrane calcium ATPases (PMCAs) are a family of proteins that actively control the level of cytosolic Ca²⁺ by pumping Ca²⁺ out of the cell. The four PMCA isoforms (PMCA1-4) show differential patterns of expression with PMCAs 1 and 4 being ubiquitously expressed and PMCAs 2 and 3 being expressed almost exclusively in brain tissue. We propose that PMCAs are important for synapse function, firstly by virtue of their Ca²⁺ extrusion properties but secondly by virtue of molecular interactions with synapse associated proteins. Immunohistochemistry of rat and mouse cerebellar slices revealed extensive expression of PMCA2 and 3 at Purkinje cell membranes and throughout the molecular layer and granule cell layers. PMCA2 was most evident in the molecular layer whilst PMCA3 showed greatest expression in the granule cell layer. Both PMCAs co-localised with the pre-synaptic proteins synaptophysin and syntaxin and the post-synaptic density protein PSD95 in the molecular and granule cell layers. In addition, both PMCAs were enriched in synaptosome preparations, with some of each found in the pre-synaptic and post-synaptic fractions. Furthermore, the analysis of proteins that co-immunoprecipitate with PMCAs by mass spectrometry and Western Blotting revealed in vivo interactions between PMCAs and synaptic proteins. Our results provide support for a role for PMCAs at cerebellar synapses at both pre- and post-synaptic locations. We conclude that PMCAs are enriched at synapses within the cerebellum. Furthermore, the ability of PMCAs to associate with synaptic protein complexes supports the idea that this important Ca²⁺ extrusion mechanism contributes to synapse function by being in the right place at the right time.