Abstract: Plasma membrane Ca2+ ATPases (PMCAs) maintain intracellular Ca2+ homeostasis and participate in the local regulation of Ca2+ signaling. Spatially separate demands for Ca2+ regulation require proper membrane targeting of PMCAs, but the mechanism of PMCA targeting is unknown. Using the PMCA2b carboxyl‐terminal tail as yeast two‐hybrid bait, we isolated a novel PDZ domain‐containing protein from a human brain cDNA library. This protein, named PISP for PMCA‐interacting single‐PDZ protein, consists of 140 amino acids and contains little else besides a single PDZ domain. Pulldown experiments showed that PISP interacts with all PMCA b‐splice forms. PISP was found to be ubiquitously expressed and, in MDCK cells, was present in a punctate pattern throughout the cytosol and at the basolateral membrane. When added to microsomal membranes expressing PMCA4b, PISP was unable to stimulate the PMCA‐dependent ATPase activity. Our data suggest that PISP is a transiently interacting partner of the PMCA b‐splice forms that may play a role in their sorting to or from the plasma membrane.