The fundamental properties of Homer 1 in association with cardiac ryanodine receptor in mouse heart.

BACKGROUND Homer, known as a scaffolding protein that regulates postsynapse signaling in neurons, has been poorly explored in cardiac research. We show the fundamental properties of Homer 1 in mouse heart in association with cardiac ryanodine receptor (RyR), a binding protein of Homer 1. METHODS AND RESULTS Immunohistochemistry of adult mouse heart with Homer 1 antibody showed striated staining on Z-bands both in atria and ventricles. The interactions between Homer 1 and RyR were confirmed by co-immunoprecipitation assays. Immunostaining of adult isolated cardiomyocytes showed partial co-localization of both proteins. In neonatal primary cultures, targeting of Homer 1 preceded that of RyR in their Z-band arrangement. CONCLUSIONS Homer 1 binds to RyR in adult mouse heart and precedes RyR in Z-band arrangement in the early postnatal period.