Studies on the synthesis and intracellular accumulation of protocollagen in organ culture of embryonic cartilage.
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Organ cultures of embryonic cartilage were prepared which synthesized collagen at a relatively constant rate for up to 72 h. When protocollagen hydroxylase in the tissue was inhibited by adding ,-dipyridyl to the medium, the incorporation of [14C]proline continued at 43 to 72% of the control rate but no collagen hydroxy[14C]proline was synthesized. Assays of tissue homogenates for protocollagen hydroxylase activity indicated that the inhibition of the enzyme by ,-dipyridyl became irreversible with time so that about half of the enzymatic activity was irreversibly lost in 4 to 6 h, and only 10% of the initial activity was recovered after 72 h. Digestion of tissue homogenates with purified collagenase indicated that under control conditions about half of the 14C incorporated from [14C]proline was in [14C]collagen, and in the presence of ,-dipyridyl about half of the 14C incorporated was in [14C]protocollagen. Pulse-labeling of the tissue indicated that a large part of the [14C]protocollagen synthesized early in the culture period was retained by the tissue for up to 72 h. Fractionation of tissues pulse-labeled for 6 h indicated that there was a progressive decrease in the amount of [14C]protocollagen recovered in the 100 000 g supernatant fraction, and a complementary increase in the amount of [14C]protocollagen in the 100 000 g sediment. Autoradiographs of tissues cultured with [3H]proline indicated that the protocollagen remained intracellular for up to 72 h whereas the collagen synthesized under control conditions was rapidly extruded into the matrix. 1968.
author list (cited authors)
Bhatnagar, R. S., Kivirikko, K. I., & Prockop, D. J.
complete list of authors
Bhatnagar, RS||Kivirikko, KI||Prockop, DJ