[Intracellular localization of fibronectin-synthesizing polyribosomes using I125 collagen]

Interaction of 125I-collagen with fibronectin-synthesizing polyribosomes, isolated from 9 days old chicken embryos, was studied. The interaction was maximal at the ratio of 0.1 microgram 125I-collagen and 5 ou of polyribosomes. Specific reaction of 125I-collagen with fibronectin polypeptides growing on polyribosomes was estimated by means of antibodies to fibronectin inhibiting the complex formation of polyribosomes-125I-collagen. The antibodies were shown to decrease the reaction rate of total polyribosomes (free and membrane-bound) with 125I-collagen by 25.4% and of free polyribosomes - by 6.7%. The data obtained suggest that fibronectin is synthesized mainly on polyribosomes, bound with the membranes of endoplasmic reticulum.