Fig. 2

Contractile activation induces the dissociation of PP1, but not PP2A, from vimentin in smooth muscle. a Representative immunoblots illustrating the interaction of PP1 with vimentin. Mouse tracheal rings were stimulated with acetylcholine (ACh, 10⁻⁴ M, 5 min) or left unstimulated. Extracts of these tissues were immunoprecipitated using vimentin antibody, and blotted with use of antibodies against PP1 and vimentin. PP1 antibody, but not IgG, immunoprecipitates PP1 and vimentin. The ratios of PP1 to vimentin in the ACh-treated tissues are normalized to those in untreated tissues. *Significantly lower ratio of PP1/vimentin in ACh-treated rings as compared to untreated tissues (p < 0.05). Data are mean ± SE (n = 5). b Extracts of tissues treated with or without ACh (10⁻⁴ M, 5 min) were immunoprecipitated with vimentin antibody, and blotted with use of antibodies against PP2A and vimentin. PP2A is barely present in vimentin immunoprecipitates. The ratios of PP2A to vimentin in the ACh-treated tissues are normalized to those in untreated tissues. N.S., not significant (p < 0.05). Data are mean ± SE (n = 5)