Tissue-specific subcellular immunolocalization of a myosin-like protein in maize root apices

Using a heterologous myosin antibody raised against the whole molecule of bovine muscle myosin, we have identified a myosin-like protein in maize. Immunoblots of subcellular fractions isolated from roots identified one distinct band at about 210 kDa in the microsomal protein fraction and one band at about 180 kDa in the soluble protein fraction. Indirect immunofluorescence was performed using maize root apex sections to reveal endocellular distributions of the myosin-like protein. Both diffuse and particulate labelling patterns were observed throughout the cytoplasm of all root cells. In mitotic cells, myosin-like protein was excluded from spindle regions. Amyloplast surfaces were labelled prominently in cells of the root cap statenchyma and in all root cortex cells. On the other hand, myosin-like protein was prominently enriched at cellular peripheries in cells of the pericycle and outer stele in the form of continuous peripheral labelling. From all root apex tissues, phloem elements showed the most abundant presence of myosinlike protein.