Fig. 8. FKBP12 and FKBP12.6 detection in whole brain and colon and the effects of recombinant FKPB12.6 on Ca²⁺ release and cADPR. (A) immunoblots were probed with SA168 antiserum (Ai) and C-19 polyclonal antibody (Aii), respectively. Lanes 1 and 2 were loaded with recombinant FKBP12 and FKBP12.6, respectively (200 ng each), lanes 3-5 with 25, 50 and 75 µg, respectively, total brain homogenate, and lanes 6-8 with the same amounts of total homogenate from colon. FKBP12 and/or FKBP12.6 were detected in brain and colon by SA168 as shown by bands at the 12 kDa level. The detection of bands at the 12 kDa level by C-19 suggests that only FKBP12 is present in myocytes (n=3). (B) Recombinant FKBP12.6 (1 ng ml^–1 via the patch pipette) significantly reduced the magnitude of STOCs (i) evoked by membrane depolarization (iii, –70 mV to –30 mV, P<0.05) but cADPR () remained ineffective in altering [Ca²⁺]_c or STOCs. (C) There was no significant change in STOC frequency or amplitude over a comparable timescale in separate time-matched control experiments in the absence of FKBP12.6 (Ci expanded time base, ii). (D) Lanes 1-3, shows 100 µg loads of total brain homogenate, lane 4 shows recombinant FKBP12 (200 ng) and lane 5 shows FKBP12.6 (200 ng; Di). Brain homogenate was treated with either FK506 (20 µM; lane 2) or cADPR (50 µM; lane 3) and subjected to electrophoresis. The results are representative of three independent experiments. Developed immunoblots were subjected to densitometric analysis (optical density, O.D.) and results normalized to the standard amount of recombinant FKBP12 loaded on each gel. (ii) Summary of experiments, control and FK506 (n=4) cADPR (n=3; *P<0.05).