title: Reciprocal control of the conformational state of the sarcoplasmic reticulum calcium channel protein by polarization and depolarization in the transverse tubule.
abstract: We attached the conformational probe methylcoumarin acetate (MCA) specifically to the junctional foot protein (JFP) moiety of triads, and monitored conformational changes in the JFP during polarization and depolarization of the T-tubule moiety. The MCA fluorescence decreased upon T-tubule polarization, and the fluorescence changes were blocked by preventing T-tubule polarization or by a nimodipine block of the T-tubule-to-sarcoplasmic reticulum communication. Depolarization of the T-tubule reversed the MCA fluorescence decrease which had been produced by T-tubule polarization. These results suggest that the conformational and functional states of the JFP are regulated by T-tubule polarization and depolarization in a reciprocal fashion.
authors.affiliation: Boston Biomedical Research Institute, MA 02114, USA.
authors.forename: N
authors.initials: N
authors.lastname: Ikemoto
authors.forename: R
authors.initials: R
authors.lastname: El-Hayek
mesh_terms: D000818:Animals; D015220:Calcium Channels / Q000502:physiology*; D020746:Calcium Channels, L-Type; D003374:Coumarins / Q000737:chemistry; D008564:Membrane Potentials / Q000502:physiology*; D008954:Models, Biological; D015335:Molecular Probes; D009119:Muscle Contraction / Q000502:physiology; D009124:Muscle Proteins / Q000502:physiology*; D009210:Myofibrils / Q000502:physiology*; D011487:Protein Conformation; D011817:Rabbits; D019837:Ryanodine Receptor Calcium Release Channel; D012519:Sarcoplasmic Reticulum / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D003374:Coumarins; D015335:Molecular Probes; D009124:Muscle Proteins; D019837:Ryanodine Receptor Calcium Release Channel; C030123:coumarin