Fig. 4.
RACK1 modifies purinergic influences on IP3R function. (A) Western blots of rat PC12 cell lysates and human HEK cell lysates, respectively, transfected for 56 h with YFP alone (input), YFP plus siRNA RACK1 duplex (specific to cell species), or YFP plus siRNA duplex plus RACK1 (opposite to siRNA species). Gels were transferred and blotted with a polyclonal antibody specific for RACK1. Free Ca2+ measurements were made in rat PC12 cells transfected for 60 h with either YFP alone (black trace), YFP plus RACK1 (red trace), or YFP plus siRNA (blue trace). (B and C) Ca2+ pools were released in cells by UTP (100μM; arrow) in nominally Ca2+-free medium followed by replacement with UTP and normal 1 mM Ca2+ medium (bar). (D) As in B and C except with pretreatment with the PKC inhibitor GF-109203X (GF, 1 μM; first bar). Traces in B–D are averaged from multiple (30–50) cells.