title: Labelling of prolyl hydroxylase tetrameric subunits in freshly isolated chick-embryo tendon cells and in certain chick-embryo tissues in vivo.
abstract: The labelling of the subunits of prolyl 4-hydroxylase tetramers was studied in freshly isolated chick-embryo tendon cells and in chick-embryo tissues. In the former both the alpha- and beta-subunits of the tetramer were labelled during a 4 h labelling and 2 h chase period, although the radioactivity in the beta-subunit was much lower than in the alpha-subunit. The corresponding subunits of the enzyme from 12-day chick-embryo cartilaginous bone and heart were labelled in 7 h, again the beta-subunit much less than the alpha-subunit, the ratio of radioactivity in the beta-subunit to that in the alpha-subunit (beta/alpha-radioactivity) being 0.20 and 0.32 respectively. The beta/alpha-radioactivity then increased almost linearily with time between 7 and 24 h, by 9.5-fold in the cartilaginous bone and 3-fold in the heart, and beta/alpha-radioactivity values above 1.0 were reached. The free beta-subunit-size protein (the beta'-protein), which is also present in cells, had been labelled quite heavily by 7 h. The beta/alpha-radioactivity at 7h, determined in four tissues with different ratios of prolyl hydroxylase tetramers to total immunoreactive protein (tetramer percentage), was low in tissues with a high tetramer percentage. It is thus proposed that only a minor fraction of the beta'-protein must be processed to the tetrameric beta-subunit and utilized in the synthesis of the prolyl 4-hydroxylase tetramers.
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000196:embryology / Q000201:enzymology; D002642:Chick Embryo; D006321:Heart / Q000196:embryology; D066298:In Vitro Techniques; D009206:Myocardium / Q000201:enzymology; D011393:Procollagen-Proline Dioxygenase / Q000378:metabolism*; D013710:Tendons / Q000166:cytology / Q000196:embryology / Q000201:enzymology*; D014316:Tritium
chemical_list: D014316:Tritium; D011393:Procollagen-Proline Dioxygenase