Phosphoprotein


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Phosphoprotein

 

any of the conjugated proteins containing a phosphoryl group bonded to the amino acid residues of the polypeptide chain. Usually, the phosphoryl group (—PO32–) is bonded to the phosphoprotein molecule through residues of the amino acids serine and threonine; in the mitochondria in animal tissues, phosphoproteins have been found in which the phosphoryl group is bonded to the protein through the imidazole ring of histidine. The transfer of the phosphoryl residue to the protein is catalyzed by the enzyme protein kinase, one of the phosphotransferases; here, adenosine triphosphate is the phosphate donor. Alkalies bring about a nonenzymatic separation of the phosphoryl group; in the presence of acids, however, phosphoproteins are relatively stable.

Phosphoproteins include casein, a basic protein in milk, and ovalbumin and vitellin, which are present in eggs. Also included are phosphorylated modifications of histones, RNA polymerases, certain phosphotransferases, and phosphatases. Phosphoproteins are very common in living organisms, where they figure in metabolism, in the regulation of the activity of cell nuclei, in ion transport, and in oxidation processes in mitochondria.

REFERENCE

Lisovskaia, N. P., and N. B. Livanova. Fosfoproteiny. Moscow, 1960.

V. V. ZUEVSKII

References in periodicals archive ?
Megakaryocyte hyperplasia and enhanced agonist-induced platelet activation in vasodilator-stimulated phosphoprotein knockout mice.
[4] Nonstandard abbreviations: PTCA, percutaneous transluminal coronary angioplasty; ASA, acetylsalicylic and (aspirin); FACS, fluorescence-activated cell sorting; PKA, cAMP-dependent protein kinase; P-VASP, phosphorylated vasodilator-stimulated phosphoprotein; EIA, enzyme immunoassay; ABTS, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt; FITC, tluorescein isothiocyanate; PRP, platelet-rich plasma; PBS, phosphate-buffered saline; MFI, geometric mean fluorescence intensity; PRI, platelet reactivity index; and [PGE.sub.1], and [PGI.sub.2], prostaglandin [E.sub.1] and [I.sub.2] (prostacyclin), respectively.
Borna disease virus phosphoprotein represses p53-mediated transcriptional activity by interference with HMGB1.
Icariin exterts negative effects on human gastric cancer cell invasion and migration by vasodilator-stimulated phosphoprotein via Rac1 pathway.
Nucleolin: The most abundant multifunctional phosphoprotein of nucleolus.
Phosphoprotein stained two-dimensional gel images of induced plasma from c) P.
Sobel, "Identification and molecular characterization of Unc-33-like phosphoprotein (Ulip), a putative mammalian homolog of the axonal guidance-associated unc-33 gene product," The Journal of Neuroscience, vol.
Phosphoprotein analysis revealed two proteins that were significantly less phosphorylated in livers of [LDLR.sup.-/-]; [macLRP1.sup.-/-] mice, GSK3a (S21) and p38 MAPK (T180, Y182), and no change in GSK3[beta] (Y216) (Figure 3(b)).
OPN, a secreted phosphoprotein, has significantly lower expression in the aged group (Figure 4(f)).
The short arm of chromosome 5 harbors some genes possibly related to the development of breast cancer: DAB2 (5p13.2) encodes a mitogen-responsive phosphoprotein, downregulated in ovarian carcinoma cell lines, for which a role as tumor suppressor is suggested.
There are different PFT instruments which are widely used to assess antiplatelet drugs such as the optical light transmission aggregometry (LTA) [105], the VerifyNow[R] system (VN) (Accumetrics Inc., San Diego, California) [106], the vasodilator stimulated phosphoprotein phosphorylation assay (VASP-P) [107, 108], the multiple electrode platelet aggregometry (MEA) [105], the platelets function analyser (PFA-100) [109-111], the Impact-R assay [110], and the platelet-works[R] (PW) [110].