Serine phospho

Fig. 1. Chemical stmcture of phosphatidylcholine (PC) (1) and other related phosphohpids. R C O represents fatty acid residues. The choline fragment may be replaced by other moieties such as ethanolamine (2) to give phosphatidylethanolamine (PE), inositol (3) to give phosphatidylinositol (PI), serine (4), or glycerol (5). IfH replaces choline, the compound is phosphatidic acid (6). The corresponding lUPAC-lUB names ate (1), l,2-diacyl-t -glyceto(3)phosphocholine (2), l,2-diacyl-t -glyceto(3)phosphoethanolamine (3), 1,2-diacyl-t -glyceto(3)phosphoinositol (4), 1,2-diacyl-t -glyceto(3)phospho-L-serine and (5), l,2-diacyl-t -glyceto(3)phospho(3)-t -glycetol.

PHOSPHOPROTEINS. These proteins have phosphate groups esterified to the hydroxyls of serine, threonine, or tyrosine residues. Casein, the major protein of milk, contains many phosphates and serves to bring essential phosphorus to the growing infant. Many key steps in metabolism are regulated between states of activity or inactivity, depending on the presence or absence of phosphate groups on proteins, as we shall see in Chapter 15. Glycogen phospho-rylase a is one well-studied example. 

Protein dephosphorylation is catalyzed by phospho-hydrolases called protein phosphatases. While the number of protein tyrosine kinases is roughly comparable to the number of protein tyrosine phosphatases, protein serine-threonine kinases vastly outnumber the protein serine-threonine phosphatases, of which about 25 different species are known to exist. This relative under-representation may be accounted for by the alternative diversification... 

The PS-induced apoptosis was highly specific for PS. Synthetic PS analogs such as l,2-diacyl-5n-glycero-3-phospho-D-serine (D-PS), 1,2-diacyl-sn-glycero-3-phospho-homoserine (P-H-S), 1,2-diacyl-sn-glycero-3-phospho-serine methyl esther (PS-O-Me), and 2,3-diacyl-sn-glycero-l-... 

Adams RR, Maiato H, Earnshaw WC, Carmena M (2001) Essential roles of Drosophila inner centromere protein (INCENP) and aurora B in histone H3 phosphorylation, metaphase chromosome ahgnment, kinetochore disjunction, chromosome segregation. J Cell Biol 153(4) 865-880 Ahn SH, Cheung WL, Hsu JY, Diaz RL, Smith MM, Alhs CD (2005a) Sterile 20 kinase phospho-rylates histone H2B at serine 10 during hydrogen peroxide-induced apoptosis in S. cerevisiae. Cell 120(l) 25-36... 

The regulatory roles of 14-3-3 proteins are realized by their binding to the phosphothreonine or phospho-serine motifs in the targets. Yao etal suggested that the phosphorylated Arg-X-Ser-X motif in the C-termini of ACS of types 1 and 2 is a potential binding site of 14-3-3 proteins in vivo and thus 14-3-3 proteins can play some role in the protection of ACS polypeptides from proteasomal degradation. 

Example 24 preparation of an asymmetrically-protected phospho-roamidite 0-tert-butyl-0-2-cyanoethyl-iV,iSr-diisopropylphosphoroamidite as a phosphitylating reagent in the synthesis of phosphopeptides has been described by Toth s group. [52]. This reagent allows the efficient synthesis of serine and threoine containing phosphopeptides by the global approach. 

This pyridoxal-phosphate-dependent enzyme [EC 2.6.1.52] catalyzes the reaction of O-phospho-L-serine with a-ketoglutarate (or, 2-oxoglutarate) to produce 3-phosphonooxypyruvate and L-glutamate. 

It has been shown that phosphorylation changes the local conformation of a protein and thereby affects the activity of the complete protein. 341 Phosphorylation of serine and threonine side chains often occurs (Scheme 2). Phosphoamino acids are readily characterized using 3H and 31P NMR experiments. The H and 31P NMR parameters are distinct for phosphorylated serine, threonine, and tyrosine and have also been used to identify both cis-and trans-O-phospho-4-hydroxy-L-proline. 35 Phosphorylation of Cys is rare, but it can be identified by NMR even in large proteins. 36 ... 

ATP -I- low-density lipoprotein L-serine = ADP 4- low-density lipoprotein O-phospho-L-serine... 

The protein tyrosine phosphatases also exist as several families with numerous functions in control of transcription, growth, differentiation, and metabolism.741-743 These enzymes function by a doubledisplacement mechanism, as in Eq. 12-38, but with a cysteine side chain rather than serine. The cysteine is present in the conserved sequence (H/V)CX5R(S/T). The arginine binds the phospho group and helps to stabilize the transition state, which probably is metaphosphate-like.742... 

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