Threonine identification

It was straightforward to identify the spin systems of four valines, five threonines, four alanines, three glycines, two glutamates, and AMX type residues (Asp, Cys, Phe, Tyr, Trp, and Ser) of this protein from the COSY, RELAY, and NOESY spectra in D O solution. The RELAY spectrum was particularly useful in identification of Val, Ala, Thr, and Glu spin systems. 

Ahn, N. G., Weiel, J. E., Chan, C. P., and Krebs, E. G. (1990). Identification of multiple epidermal growth factor-stimulated protein serine/threonine kinases from Swiss 3T3 cells. J. Biol. Chem. 265 11487-11494. 

Arden, S.R., Smith, A.M., Booth, M.J., Tweedie, S., Gounaris, K. and Selkirk, M.E. (1997) Identification of serine/threonine protein kinases secreted by Trichinella spiralis infective larvae. Molecular and Biochemical Parasitology 90, 111-119. 

Identification of serine/threonine protein kinases secreted by Trichinella spiralis infective larvae. Molecular and Biochemical Parasitology 90, 111-119. 

Filamentous tau is hyperphosphorylated. This is an early event that appears to precede filament assembly. It also renders tau unable to interact with microtubules. Much effort has gone into the mapping of phosphorylation sites and the identification of candidate protein kinases and phosphatases. For sites that are also phos-phorylated in normal brain tau, a higher proportion of tau molecules is phosphorylated in filamentous tau. In addition, filamentous tau is phosphorylated at more serine and threonine residues than tau from normal adult brain. Phosphorylation-dependent anti-tau antibodies were instrumental for the study of many phosphorylation sites. In particular, phosphorylation of S214 and S422 was found to be specific for assembled tau. 

Other PTMs may involve changes in the chemical nature of amino acids (e.g., citrullination or deimination). Because many of these modifications result in mass changes that are measurable by MS, they are amenable to detection by MS-based approaches. A number of emerging MS-based strategies allow the identification of PTMs. Several MS-based methods to determine the types and sites of protein phosphorylation and ubiquitination have been developed. Phosphorylation occurs mainly on serine, threonine, and tyrosine residues at a frequency ratio of 1800 200 1 in vertebrates.70 Although the phosphorylation of tyrosine residues occurs less frequently in the proteome, it has been extensively studied. 

The complete identification of the amino acids which are essential in the diet is due to W.C. Rose (1938). His first attempts to replace casein with its constituents were unsuccessful because an essential amino acid component in the protein hydrolysate had been missed. After threonine had been isolated by him from casein and fibrin, and shown to be essential, Rose identified val, met, his, lys, phe, leu, ile, thr, and arg as... 

Identification of associated protein kinases Based on phosphopeptide analyses it became clear that associated kinases modify principally serine and threonine residues. Moreover, the analysis of putative phosphorylation-speciflc consensus sequences of p53, c-Jun, p27, ICSBP and I/cBa revealed that the protein kinase CK2 and a member of the protein kinase C family might be associated with the CSN. 

Nezu J, Oku A, Jones MH, Shimane M (1997) Identification of two novel human putative serine/threonine kinases, VRKl and VRK2, with structural similarity to vaccinia virus BIR kinase. Genomics... 

Palmer, T. M., Stiles, G. L. (2000) Identification of threonine residues controlling the agonist-dependent phosphorylation and desensitization of the rat A(3) adenosine receptor [in process citation]. Mol Pharmacol 57, 539-545. 

Aliphatic hydroxyl groups cannot normally be selectively modified except in certain special cases such as the serine proteinases. In anhydrous formic acid, the A,O-acyl migration that occurs in strong sulfuric or phosphoric acid apparently does not occur. Instead there is formylation of the serine and threonine residues (208). Enzymically inactive aggregates are produced, but the reaction is reversed in aqueous solution at neutral pH and the activity returns. Josefsson reported the introduction of 29 formyl groups in RNase (209) as compared to the total of 25 Ser and Thr residues. This identification of reaction sites is not clear, however, since the number of formyl groups introduced into lysozyme far exceeded the Ser-Thr total. 

Murphy CD, O Hagan D, Schaffrath C (2001) Identification of a PLP-Dependent Threonine Transaldolase A Novel Enzyme Involved in 4-Fluorothreonine Biosynthesis in Streptomyces cattleya. Angew Chem Int Ed 40 4479... 

M Offenzeller, G Santer, K Totschnig, Z Su, H Moser, R Traber, E Schneider-Scherzer. Biosynthesis of the unusual amino acid (4R)-4-[(E)-2-butenyl]-4-methyl-L-threonine of cyclosporin A enzymatic analysis of the reaction sequence including identification of the methylation precursor in a polyketide pathway. Biochemistry 35 8401-8412, 1996. 

With the identification of calcineurin-mediated NF-ATc translocation in T cells, a model of the cytosolic events involved in T-cell activation has emerged, as oudined in Fig. 4. Stimulation of the TCR results in a series of membrane-associated events culminating in a rise in intracellular Ca2+, which binds to and activates calmodulin/calcineurin. Activated calcineurin then causes the cytoplasmic-to-nuclear translocation of NF-ATc, an event potentially mediated via the dephosphorylation of critical serine and/or threonine residues on the NF-ATc protein (Beals et al., 1997a, 1997b). Once nuclear, NF-ATc binds DNA with its nuclear partner, NF-ATn to drive production of IL-2 and other early genes, leading to lymphocyte activation and proliferation. 

Hawley, S. A., Davison, M., Woods, A., Davies, S. P., Beri, R. K., Carling, D., and Hardie, D. G. 1996. Characterization of the AMP-activated protein kinase kinase from rat liver and identification of threonine 172 as the major site at which it phosphorylates AMP-activated protein kinase. J Biol Chem 271 27879-27887. 

ApoSAA, normally a trace component of plasma, is an acute-phase plasma protein, that is, one that is elevated in a variety of disease states (R18). Its identification is interesting. A small protein of 76 residues, now called protein AA, was identified during the study of the proteins present in extracellular amyloid deposits in the type of amyloidosis particularly associated with inflammation (B24, H36, Lll, S38), Antibodies to protein AA reacted with two AA-related proteins in plasma, one of approximate Mr 180,000 (SAA) and the other found in HDL of Mr 14,000-15,000 or 12,000 (apoSAA) (A19, B25, B26, L12, L15). The N-terminal 76-amino-acid portion of apoSAA is identical to that of amyloid protein AA (E8). Human apoSAA has now been sequenced and has been shown to consist of 104 amino acid residues (B27). Further studies in man have demonstrated microheterogeneity in apoSAA (B18, B19, M30) and Benditt et al. describe specific amino acid substitutions (B27, P6). Shore et al. have described a second similar threonine-poor apolipoprotein, apparently a dimer of Mr 40,000... 

W. Baltes and G. Bochmann, Model reactions on roast aroma formation. IV. Mass spec-trometric identification of pyrazines from the reaction of serine and threonine with... 

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