Abstract
To obtain two different cell populations derived from human alveolar bone, bone fragments were divided into two groups, and cultured separately as described in a previous report (J. Japan Ass. Periodont., 33: 101-109, 1991). One group of cells, E-AB, was obtained from collagenase-treated bone fragments, and the other, N-AB, was from untreated bone fragments. Protein synthesis was determined by 24hr 14C-proline labeling using confluent cells in 35mm Falcon™ dishes. According to the results of the radiolabeling, the E-AB showed slightly higher incorporation than the N-AB's, however the total protein synthesizing ability of the two cell populations was almost the same. This difference may result from gene expressions for collagenous protein synthesis possessed by both cell populations: the E-AB secreted 12.5% of the collagenous proteins among the total proteins, whereas the N -AB secreted about 2% fewer collagens . After the proteins were digested with bacterial collagenase or cyanogen bromide, SDS-PAGE and fluorography were carried out to determine the Mrs of collagenase-or cyanogen bromide-resistant proteins. The intensity of two protein bands in the region of 25 to 28 kDa increased after collagenase digestion. All the proteins secreted into the cultured media, except for the 28 kDa protein, were fragmented into small peptides by cyanogen bromide treatment. Large quantities of type I and about 9% of type III collagens were secreted by both cell populations. All the proteins and the proportions of the above collagen types in both cultured media were virtually the same, except that the E-AB secreted somewhat more 28 kDa and 34 kDa protein than did the N-AB.
