Threonine characteristics

G-protein-coupled receptor kinases (GRKs) are a family of enzymes that catalyze the phosphorylation of threonine or serine residues on G-protein-coupled receptors. Characteristically, GRKs only phosphorylate the ligand-activated form of the receptors. Phosphorylation by GRKs usually leads to impaired receptor/G-protein coupling. 

S6K1 (also known as p70S6 kinase) is a serine/ threonine protein kinase which is involved in the regulation of translation by phosphorylating the 40S ribosomal protein S6. Insulin and several growth factors activate the kinase by phosphorylation in a PI 3-kinase dependent and rapamycin-sensitive manner. Phosphorylation of S6 protein leads to the translation of mRNA with a characteristic 5 polypyrimidine sequence motif. 

C17-0017. Describe the acidic and basic characteristics of the amino acids histidine and threonine. 

Characteristically, legume seeds are rich in protein and contain intermediate to high levels of lysine and threonine which are important in balancing the deficiencies of these essential amino acids in cereal diets. Certain legume proteins, such as soybean, also exhibit strong functional properties, especially water solubility, water and fat binding and emulsification. Thus soybean flours, protein concentrates and isolates have been used widely as nutritional supplements and functional ingredients in foods. 

Also referred to as apo LP-Gln for its COOH-terminal residue, this has been shown to have threonine as its NHa-terminal residue. Its amino acid composition (Table 9) shows characteristics that are distinct from the... 

From these data, there is now good evidence that PA is electronically coupled to Pb and is thus involved in P7oo- The decrease in spin density on PB (Table 5) in all threonine mutants can be interpreted as a spin density shift from Pb towards PA. The effect of H-bonding to P7q0 shows the same characteristics as for QA in... 

Protein kinases can be classified according to the amino acid residue that is phosphorylated in the cellular process. Consequently, there are tyrosine-specific kinases and serine/threonine kinases. Tyrosine kinases are a family of tightly regulated enzymes, and the aberrant activation of various members of this family is one of the hallmarks of cancer. Tyrosine phosphorylation has been linked to multiple cell growth and differentiation pathways. Imatinib mesylate (1) is a tyrosine kinase inhibitor (TKI). An important characteristic of imatinib mesylate (1) is that it is an ATP-competitive inhibitor. It binds at the ATP binding site and blocks ATP binding thereby inhibiting kinase activities. 

Primary cell-walls of dicots contain between 5 and 10% of protein that is rich (20%) in hydroxy-L-proline.4,55,228 The wall protein also contains a relatively high content of L-alanine, L-serine, and L-threonine, and this feature is found in such animal structural-proteins as collagen.228 This characteristic, amino acid composition, together with the fact that it is difficult to extract much of the protein from cell walls under nondegra-dative conditions,229 suggests that it has a structural role in the wall.228-230... 

Is and PBPRP1 may then represent an OBP-1 type of protein defined by key residues that may underlie specific functions. The ABPX/PBPRP-specific amino acid residues arginine at position 16, lysine at position 47, proline at position 76, threonine at position 92 are replaced respectively by leucine, glycine, lysine and lysine residues that are conserved in the different types of binding protein from B. mori (Krieger et al., 1993 Picimbon, 2001). These replacements may be relevant to support the function of ABPX. Based on the crystal structure of the bombykol-PBP complex, the tryptophane at position 101 and the valine 105 have been shown to contact the molecule of Bombykol (Sandler et al., 2000). These are replaced by two threonine residues characteristic of OBP-1. Therefore, the threonine residues characteristic of OBP Is may be of crucial importance for the binding specificities of these proteins. 

Core structures of mucin-type O-linked glycans. These represent a series of characteristic structures attached to a serine (S) or threonine (T) amino acid residue of a protein. There are eight core structures, each of which may have further monosaccharide additions. Tn is a precursor of theT (Thomsen-Freidenreich) antigen which is commonly used as a marker for tumor cells. 

Cyclosporines (Fig. 7) are cyclic undecapeptides composed of 11 amino acids — some of them N-methylated — in which the amino acid (4R)-4-[(E)-2-butenyl]-4,N-di-methyl-L-threonine (MeBmt) 59 is a characteristic component and plays a consider-... 

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