ANU Open Research Repository has been upgraded. We are still working on a few minor issues, which may result in short outages throughout the day. Please get in touch with repository.admin@anu.edu.au if you experience any issues.
 

In vitro modulation of the cardiac ryanodine receptor activity by Homer1

Date

2009

Authors

Pouliquin, Pierre
Pace, Suzy M
Dulhunty, Angela

Journal Title

Journal ISSN

Volume Title

Publisher

Springer

Abstract

The Homer protein family allows clustering and/or functional modulation of many proteins from different calcium signalling complexes including those formed by the ryanodine receptor (RyR) Ca2+ release channel in skeletal muscle and the heart. Homer1b/c and the cardiac RyR (RyR2) are strongly expressed in the heart and neurons where their interaction with each other may modulate Ca2+ signalling. However, functional interactions between Homer1b and RyR2 have been poorly defined. Our preliminary data and similar consensus binding sites for Homer in RyR2 and skeletal RyR (RyR1) proteins, led to the hypothesis that Homer may similarly regulate both RyR isoforms. Single-channel and [3H]ryanodine binding data showed that RyR2 and RyR1 activity increased to a maximum with ~50-100 nM Homer1b and fell with Homer1b > 200 nM. Homer1b (50 nM) activated RyR2 and RyR1 at all cytosolic [Ca2+]; estimated EC50 value of RyR2 diminished from ~2.8 μM Ca2+ (control) to ~1.9 μM Ca2+ in the presence of 50 nM Homer1b. Short Homer1 (lacking the coiled-coil multimerisation domain) and Homer1b similarly modulated RyR2, indicating an action through ligand binding, not mutimerisation. These actions of Homer were generally similar in RyR2 and RyR1. The strong functional interactions suggest that Homer1 is likely to be an endogenous modulator of RyR channels in the heart and neurons as well as in skeletal muscle.

Description

Keywords

Keywords: calcium channel; hybrid protein; ion channel; protein homer 1; ryanodine receptor; ryanodine receptor 1; ryanodine receptor 2; ubiquitin; animal tissue; article; binding site; calcium signaling; controlled study; Escherichia coli; heart; ligand binding; m Calcium channel; Heart; Muscle; Neuron; Ryanodine receptor

Citation

Source

Pflugers Archives European Journal of Physiology

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

DOI

10.1007/s00424-009-0664-0

Restricted until

2037-12-31