CHICKEN ANTIBODIES TO RABBIT MUSCLE ACTIN WITH A RESTRICTED REPERTOIRE OF F-ACTIN RECOGNITION

This report describes a polyclonal antibody against actin with unexpec ted and unusual properties. The antibody was raised in chicken immuniz ed with a complex of DNase I and rabbit skeletal muscle actin, and pur ified from egg yolk by affinity chromatography. In Western blots, it r eacted with alpha, beta and gamma isoforms of actin. In immunofluoresc ence and dot blot assays, however, it recognized selectively actin fil aments in myofibrils, microvilli of brush border-type epithelium and t he ''comet tails'' of the intracellular parasite Listeria monocytogene s, while it did not react with stress fibers and peripheral belts of f ibroblasts and epithelial cells, respectively. This reactivity pattern is reminiscent of that previously described for a monoclonal mouse an tibody raised against smooth muscle actin (Sawtell et al., Cell Moth. Cytoskel. 11, 318, 1988). The data presented in this study are consist ent with the hypothesis that the chicken antibody recognizes an actin epitope/actin epitopes either accessible in only a subpopulation of mi crofilaments, or expressed only in a particular conformation of F-acti n.