Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0029463 (osteosarcoma)
 16,637 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

CD9 is a signal-initiating glycoprotein of uncertain membrane insertion which contains more than one locus of acylation and is distinguished by being the major acylatable platelet protein. The N-terminus of CD9 is blocked to Edman degradation. We investigated whether [3H]myristic acid could be incorporated into CD9, whether that incorporation occurred via an amide linkage, and whether myristate and palmitate were differentially incorporated into the two domains. Pulse-labeling studies, performed on the human osteogenic sarcoma cell line SKOSC which expresses 22 and 24 kDa variants of CD9 demonstrated that the respective precursors of 20.5 and 23 kDa were not radiolabeled by either [3H]myristic acid or [3H]palmitic acid, but that both fatty acids could be ligated to CD9 during the later stages of protein maturation. The failure to incorporate myristic acid cotranslationally suggest that CD9 does not contain amino-terminal amide-bonded myristic acid. Incorporation of radiolabel from both fatty acids proceeded very rapidly and could be visualized after a 10 s pulse. Although myristic acid was partially metabolized into palmitic acid, incorporation of authentic [3H]myristate into CD9 could be demonstrated. The myristic acid bonds were shown to be as sensitive to hydroxylamine treatment as those linking palmitate. Both fatty acids were also incorporated into CD9 in hydroxylamine-sensitive bonds in the presence of cycloheximide, reaching 30-40% of the levels in untreated controls. The sensitivity of myristate ligands to hydroxylamine demonstrates that this fatty acid is not linked via amide, but rather via ester bonds. The sensitivity of [3H]myristate and [3H]palmitate bonds to 2-mercaptoethanol further suggests that either fatty acid is linked via thioester rather than hydroxyester bonds to each domain on CD9. Limited proteolysis analysis with Staphylococcus aureus V8 proteinase of CD9, labeled in the absence or presence of cycloheximide, showed that [3H]myristic acid and [3H]palmitic acid labeled identical peptides, and to the same extent, suggesting that myristate is an alternative substrate for the transacylase(s) involved.
 ...
PMID:Myristic acid is incorporated into the two acylatable domains of the functional glycoprotein CD9 in ester, but not in amide bonds. 219 73

Devitalized cultured cells of a murine osteosarcoma preserved strong osteogenic activity even after incubation in neutral and acidic buffer at 37 degrees for six days. This observation suggested that an osteosarcoma-derived osteogenic factor was considerably stable to endogenous proteases, or that osteosarcomas do not synthesize enzymes for degradation of the osteogenic factor. EDTA decalcification or extraction of the osteosarcoma at 37 degrees for six days had no apparent effect on the osteogenic factor. Disulfide-bond reducing agents (2-mercaptoethanol and dithiothreitol) completely inactivated the osteogenic activity and in the presence of guanidine HCl, the loss of activity was irreversible by reoxidation. There findings support the view that disulfide-bonds in the molecular structure of the osteogenic factor are essential for the biological activity.
 ...
PMID:Biochemical stability of a bone-inducing substance from murine osteosarcoma. 695 Aug 22

We cloned the human tartrate-resistant acid phosphatase (TRAP) gene from human osteosarcoma cells (Saos-2), and produced recombinant human TRAP (rhTRAP) using a baculovirus vector expression system. RhTRAP from Sf9 culture medium was purified by cation exchange chromatography, gel filtration and affinity chromatography. The molecular mass and amino acid composition of the rhTRAP were consistent with the deduced amino acid composition from the TRAP gene. The N-terminal amino acid sequence of rhTRAP was identical to that of TRAP purified from osteoclastoma and hairy cell leukemia spleen. The monoclonal antibodies generated against rhTRAP also reacted to human placental TRAP (pTRAP). The optimum pH of rhTRAP and pTRAP were pH 5.0-5.5 and pH 6.0-6.5, respectively. The enzymatic activities of rhTRAP and pTRAP were activated by reducing agents such as 2-mercaptoethanol, dithiothreitol and ascorbic acid. The activities of rhTRAP and pTRAP were enhanced by Fe2+ ions, but were inhibited by Fe3+ ions. The present results indicate that rhTRAP has similar properties to the native human TRAP, and suggest that the enhancement of TRAP activity by reducing agents might be expressed via the reduction of Fe ions at the metal center.
 ...
PMID:Characterizations of recombinant human tartrate-resistant acid phosphatase from osteosarcoma: comparison study between recombinant and placental proteins. 1183 17