Post-translational processing of chicken bone phosphoproteins. Identification of bone (phospho)protein kinase.
We have detected a protein kinase which phosphorylates bone phosphoproteins (BPPs) in the detergent extract of the membranous fractions in the periosteal bone strips of 12-day-embryonic-chick tibia. This enzyme, tentatively named BPP kinase, has a catalytic subunit of Mr approximately 39,000, utilizes GTP as well as ATP as a phospho-group donor, is inhibited by 2,3-bisphosphoglycerate and heparin, and is therefore similar to casein kinase II. The enzyme can phosphorylate dephosphorylated proteins such as casein, phosvitin and chicken BPPs, but the last-named are preferred substrates. The in vitro-phosphorylation-assay products of this enzyme in the extract were indistinguishable on an SDS/polyacrylamide gel from the major [32P]phosphoproteins metabolically labelled in the embryonic-chick bone tissue. The regulatory mechanisms of the phosphorylation process of BPPs by BPP kinase as well as the potential role of this enzyme in mineralization are discussed.
Mikuni-Takagaki
Y
Y
Laboratory for the Study of Skeletal Disorders and Rehabilitation, Harvard Medical School, Children's Hospital, Boston, MA 02115.
Glimcher
M J
MJ
D019794:2,3-Diphosphoglycerate; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001842:Bone and Bones / Q000196:embryology / Q000201:enzymology*; D047388:Casein Kinases; D002642:Chick Embryo; D004163:Diphosphoglyceric Acids / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000378:metabolism; D006493:Heparin / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D013977:Tibia
D004163:Diphosphoglyceric Acids; D010750:Phosphoproteins; D019794:2,3-Diphosphoglycerate; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D006493:Heparin; D011494:Protein Kinases; D047388:Casein Kinases