Is newly-secreted elastin cleaved to a smaller molecule before being incorporated into crosslinked elastin fibers?

The biosynthesis of elastin was examined in matrix-free cells isolated by enzymatic digestion of aortas from 17 day old chick embryos. When the cells were incubated with (14C) proline and then were rapidly boiled in buffer containing high concentrations of protease inhibitors and sodium dodecylsulfate, about one-quarter of the intracellular (14C)-protein was recovered as an elastin component with apparent molecular weight of about 72,000. Examination of the medium from the cell suspension indicated that the largest elastin component secreted by the cells also had an apparent molecular weight of about 72,000.