[Biosynthesis of collagen and non-collagen proteins on free and bound polysomes from chick embryo]

Synthesys of collagen and non-collagen proteins was investigated in a cell-free system in the presence of free and bound polysomes isolated from chick embryos. Of total radioactive proteins synthesized on bound and free polysomes the amount of peptides digested by bacterial collagenase comprised 25-40% and 5-7% respectively. These data showed that collagen was predominantly synthesized by bound polysomes. Free polysomes were found to be much more active than bound ones in non-collagen protein synthesis. When bound polysomes detached from membranes by detergent treatment were incubated in a cell-free system, a release of non-collagen proteins into the incubation medium increased sharply, but the release of collagen peptides was as negligible as in the case of untreated polysomes. Kinetic studies of collagen synthetizing activity of polysomes bound to or detached from membranes suggested the role of endoplasmic membranes in stabilizing collagenous polysomes.