Arterial elastin synthesis in the young chick.

In the growing chick a marked stimulation in soluble and mature arterial elastin synthesis occurs 2 and 5 weeks after hatching. Measurement of [3H]valine and [3H]proline incorporation into arterial soluble protein during this period indicated that most of the label is found in a 70 000 dalton protein subunit. The labeled soluble subunit had the characteristics of native soluble elastin or tropoelastin. During the period in which the greatest percentage increase in mature elastin occurs, the highest specific activities of soluble [3H]valine-labeled protein were observed. These changes were striking and suggest a developmental period for the growing chick in which factors related to elastin metabolism may be more easily studied.