Homer binds a novel proline-rich motif and links group 1 metabotropic glutamate receptors with IP3 receptors.
Group I metabotropic glutamate receptors (mGluRs) activate PI turnover and thereby trigger intracellular calcium release. Previously, we demonstrated that mGluRs form natural complexes with members of a family of Homer-related synaptic proteins. Here, we present evidence that Homer proteins form a physical tether linking mGluRs with the inositol trisphosphate receptors (IP3R). A novel proline-rich "Homer ligand" (PPXXFr) is identified in group 1 mGluRs and IP3R, and these receptors coimmunoprecipitate as a complex with Homer from brain. Expression of the IEG form of Homer, which lacks the ability to cross-link, modulates mGluR-induced intracellular calcium release. These studies identify a novel mechanism in calcium signaling and provide evidence that an IEG, whose expression is driven by synaptic activity, can directly modify a specific synaptic function.
SciCrunch is a data sharing and display platform. Anyone can create a custom portal where they can select searchable subsets of hundreds of data sources, brand their web pages and create their community. SciCrunch will push data updates automatically to all portals on a weekly basis. User communities can also add their own data to scicrunch, however this is not currently a free service.