This is an historical archive of the activities of the MRC Anatomical Neuropharmacology Unit (MRC ANU) that operated at the University of Oxford from 1985 until March 2015. The MRC ANU established a reputation for world-leading research on the brain, for training new generations of scientists, and for engaging the general public in neuroscience. The successes of the MRC ANU are now built upon at the MRC Brain Network Dynamics Unit at the University of Oxford.

Homer proteins and InsP(3) receptors co-localise in the longitudinal sarcoplasmic reticulum of skeletal muscle fibres.

Cell Calcium 2002;32(4):193-200.

Homer proteins and InsP(3) receptors co-localise in the longitudinal sarcoplasmic reticulum of skeletal muscle fibres.

Salanova M, Priori G, Barone V, Intravaia E, Flucher B, Ciruela F, McIlhinney RAJ, Parys JB, Mikoshiba K, Sorrentino V
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Abstract:
Striated muscle represents one of the best models for studies on Ca(2+) signalling. However, although much is known on the localisation and molecular interactions of the ryanodine receptors (RyRs), far less is known on the localisation and on the molecular interactions of the inositol trisphosphate receptors (InsP(3)Rs) in striated muscle cells. Recently, members of the Homer protein family have been shown to cluster type 1 metabotropic glutamate receptors (mGluR1) in the plasma membrane and to interact with InsP(3)R in the endoplasmic reticulum of neurons. Thus, these scaffolding proteins are good candidates for organising plasma membrane receptors and intracellular effector proteins in signalosomes involved in intracellular Ca(2+) signalling. Homer proteins are also expressed in skeletal muscle, and the type 1 ryanodine receptor (RyR1) contains a specific Homer-binding motif. We report here on the relative sub-cellular localisation of InsP(3)Rs and Homer proteins in skeletal muscle cells with respect to the localisation of RyRs. Immunofluorescence analysis showed that both Homer and InsP(3)R proteins present a staining pattern indicative of a localisation at the Z-line, clearly distinct from that of RyR1. Consistent herewith, in sub-cellular fractionation experiments, Homer proteins and InsP(3)R were both found in the fractions enriched in longitudinal sarcoplasmic reticulum (LSR) but not in fractions of terminal cisternae that are enriched in RyRs. Thus, in skeletal muscle, Homer proteins may play a role in the organisation of a second Ca(2+) signalling compartment containing the InsP(3)R, but are apparently not involved in the organisation of RyRs at triads.