title: [Biosynthesis of fibronectin by human embryonal fibroblasts transformed by SV-40 virus].
abstract: Fibronectin biosynthesis by human embryonic fibroblasts transformed with virus SV-40 was studied in intact cells and in a cell-free protein synthesizing system on free and membrane-bound polyribosomes isolated from these cells. It was found that fibronectin release from transformed fibroblasts into the culturing medium was decreased 4.5-fold, while its per cent content--2-fold. The amount of fibronectin precipitated by antibodies in the course of an immunoprecipitation reaction in transformed cells appeared to be somewhat higher than in normal cells, although when expressed on a per cent basis this content was decreased only 1.5-fold. However, the content of fibronectin monomer with Mr = 220 kD exceeded that in normal fibroblast cell material 1.6 times. Study on fibronectin biosynthesis in a cell-free system revealed that in transformed cells 45% of fibronectin is synthesized on free polyribosomes as compared to 13% in normal fibroblasts. It is assumed that the decreased fibronectin biosynthesis in human fibroblasts transformed with virus SV-40 results in spatial uncoupling of polyribosomes and membrane structures responsible for protein transport from the cell, as a result of which a significant part of fibronectin synthesized by transformed fibroblasts undergoes intracellular degradation.
mesh_terms: D002460:Cell Line; D002472:Cell Transformation, Viral; D002474:Cell-Free System; D004591:Electrophoresis, Polyacrylamide Gel; D004622:Embryo, Mammalian; D005347:Fibroblasts / Q000378:metabolism* / Q000382:microbiology; D005353:Fibronectins / Q000096:biosynthesis*; D006801:Humans; D008715:Methionine / Q000378:metabolism; D013539:Simian virus 40
chemical_list: D005353:Fibronectins; D008715:Methionine
vernacular_title: Biosintez fibronektina chelovecheskimi émbrional'nymi fibroblastami, transformirovannymi virusom SV-40.