title: Prokaryotic expression of bone sialoprotein and identification of casein kinase II phosphorylation sites.
abstract: Bone sialoprotein is an extracellular noncollagenous acidic protein that plays a role in bone mineralization and remodeling. Its expression is restricted to mineralized tissues and is subjected to variety of posttranslational modifications including phosphorylation and glycosylation. We have expressed the full-length and half domains of bovine bone sialoprotein in a prokaryotic system and identified the phosphorylation sites of casein kinase II. The N-terminal automated solid-phase sequencing defined four phosphorylated peptides: residues 28-38 (LEDS(P)EENGVFK), 51-86 (FYPELKRFAVQSSS(P)DS(P)S(P)EENGNGDS(P)S(P)EEEEEEEETS(P)), 151-165 (EDES(P)DEEEEEEEEEE), and 295-305 (GRGYDS(P)YDGQD). Nine phosphoserines were identified within the four peptides. Seven of them were in the N-terminus (S31, S64, S66, S67, S75, S76, and S86) and two were in the C-terminus (S154 and S300) of the protein.
authors.affiliation: Laboratory for the Study of Skeletal Disorders, Department of Orthopaedic Surgery, Harvard Medical School, Children's Hospital Boston, 300 Longwood Avenue, Boston, MA 02115, USA. fawzy.saad@tch.harvard.edu
authors.forename: Fawzy A
authors.initials: FA
authors.lastname: Saad
authors.forename: Erdjan
authors.initials: E
authors.lastname: Salih
authors.forename: Livius
authors.initials: L
authors.lastname: Wunderlich
authors.forename: Rudolf
authors.initials: R
authors.lastname: Flückiger
authors.forename: Melvin J
authors.initials: MJ
authors.lastname: Glimcher
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D047390:Casein Kinase II / Q000737:chemistry* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D058574:Integrin-Binding Sialoprotein; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012795:Sialoglycoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D058574:Integrin-Binding Sialoprotein; D011994:Recombinant Proteins; D012795:Sialoglycoproteins; D047390:Casein Kinase II