Figure 2. Molecular-mass shift induced in cerebellum type-I IP₃R upon reaction with MPEG-20.

(A) Cerebellum microsomes, prepared in the absence of DTT, were incubated with the indicated concentrations of MPEG-20 for 5 min at 25 °C. The samples were electrophoresed on a 5% gel and immunoblotted with CT-1 Ab. (B) shows the time course of the molecular-mass shift upon reaction with 0.5 mM MPEG-20. (C) Microsomal membranes were pre-treated with the indicated thiol reagents for 5 min at 25 °C. The concentrations used were as follows: NEM (10 mM), DTT (10 mM), TMS (1 mM) and mersalyl (1 mM). The samples were then incubated with 0.5 mM MPEG-20 for 5 min and processed for IP₃R detection as described above.