Comparative two-dimensional gel analysis and microsequencing identifies gelsolin as one of the most prominent downregulated markers of transformed human fibroblast and epithelial cells

A systematic comparison of the protein synthesis patterns of cultured normal and transformed human fibroblasts and epithelial cells, using two-dimensional gel protein analysis combined with computerized imaging and data acquisition, identified a 90-kD protein (SSP 5714) as one of the most striking downregulated markers typical of the transformed state. Using the information stored in the comprehensive human cellular protein database, we found this protein strongly expressed in several fetal tissues and one of them, epidermis, served as a source for preparative two-dimensional gel electrophoresis. Partial amino acid sequences were generated from peptides obtained by in situ digestion of the electroblotted protein. These sequences identified the marker protein as gelsolin, a finding that was confirmed by two-dimensional immunoblotting of human MRC-5 fibroblast proteins using specific antibodies and by coelectrophoresis with purified human gelsolin. These results suggest that an important regulatory protein of the microfilament system may play a role in defining the phenotype of transformed human fibroblast and epithelial cells in culture

The role of vacuolar and secreted pathogenesis-related β (1-3)-glucanases and chitinases in the defence response of plants

Upon infection of a plant by a pathogen, a series of drastic metabolic changes occur within the plant. One characteristic feature of this defence response is the synthesis of the so-called pathogenesis-related (PR) proteins. We have studied the nature, structure, and subcellular localization of the different PR proteins upon salicylic acid treatment and Pseudomonas syringae infection of Nicotiana tabacum plants. In both test systems, we could demonstrate that the PR protein fraction of tobacco consists of at least 20 to 25 different proteins, including beta (1-3)-glucanases, chitinases, peroxidases, thaumatin-like proteins, the PR1 class proteins and a proteinase inhibitor-like protein. Moreover, several classes of these PR proteins segregate into specific vacuolar and secreted isoforms. Here, we present a model which could explain the role of the compartimentalized PR beta (1-3)-glucanases and chitinases within the regulation of the defence response