Fig. 6. EDL and soleus muscle fiber area. Muscles were sectioned with a cryostat and stained with Alexa Fluor wheat-germ agglutinin (WGA-Alexa, Molecular Probes), imaged with an inverted fluorescent microscope, and analyzed as described by Briguet et al. (1). Values represent mean ± SEM. We examined 2,257 and 4,770 soleus fibers from WT and JP45 KO mice, respectively, and 3,268 and 2,757 EDL fibers from WT and JP45 KO mice, respectively. Neither EDL nor soleus fibers from JP45 KO mice were significantly different from those of WT mice.

1. Briguet A, Courdier-Fruh I, Foster M, Meier T, Magyar JP (2004) Neuromuscul Disord 14:675-682.

Fig. 7. Tetani and maximum Ca²⁺-evoked contractures were recorded in single, intact FDB fibers from WT and JP45 KO mice before and after saponin permeabilization. The asterisk indicates that the tetanus/contracture relationship differed significantly (P < 0.01). Values are mean ± SEM. The number of fibers is in parentheses. EC₅₀ and maximal contracture force were elicited by pCa 5.97 and 5.5 in WT mice and pCa 5.95 and 5.5 JP45KO mice, respectively.

Fig. 8. R1 fraction proteins from WT and JP45 KO mice used for [³H]-PN200-110 binding were separated by 7.5% PAGE, blotted, and stained with a peroxidase-conjugated antibody against albumin (Bethyl Laboratories, catalog no. A90-134P, 1:5,000 dilution), a specific protein marker of T tubule membranes (1). Densitometry of the immunopositive bands was carried out by using Bio-Rad GelDoc 2000. Values represent mean ± SEM (P > 0.05; n = 16).

1. Knudson CM, Campbell KP(1999) J Biol Chem 264:10795-10798.

Fig. 9. CaATPase activity from a purified longitudinal tubules (LSR) fraction was measured by an enzymatic-coupled assay as described by Zorzato et al. (1). The maximal CaATPase turnover rate was measured in the presence of calcium ionophore A23187. Values are the mean ± SEM of four to six determinations of three different LSR preparations.

1. Zorzato F, Salviati G, Facchinetti T, Volpe P (1985) J Biol Chem 260:7349-7355.