| tyrosine aminotransferase | <enzyme> An enzyme that catalyses the reversible reaction of l-tyrosine and alpha-ketoglutarate producing p-hydroxyphenylpyruvate and l-glutamate; this enzyme catalyses a step in l-phenylalanine and l-tyrosine catabolism; a deficiency of this enzyme is associated with tyrosinaemia II. Synonym: tyrosine transaminase. (05 Mar 2000) |
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| tyrosine decarboxylase | <enzyme> A pyridoxal-phosphate protein that catalyses the conversion of l-tyrosine to tyramine and carbon dioxide. The bacterial enzyme also acts on 3-hydroxytyrosine and, more slowly, on 3-hydroxyphenylalanine. Chemical name: L-Tyrosine carboxy-lyase Registry number: EC 4.1.1.25 (12 Dec 1998) |
| tyrosine-ester sulfotransferase | <enzyme> Also acts on phenols and organic hydroxylamines Registry number: EC 2.8.2.9 Synonym: arylsulfotransferase iv (26 Jun 1999) |
| tyrosine hydroxylase | <enzyme> Enzyme required for the synthesis of the neurotransmitters noradrenaline and dopamine. (18 Nov 1997) |
| tyrosine iodinase | A postulated enzyme in the thyroid catalyzing iodination of tyrosine, a reaction important in the eventual biosynthesis of thyroxine. See: peroxidases. (05 Mar 2000) |
| tyrosine kinase | <enzyme> Kinases that phosphorylate protein tyrosine residues. These kinases play major roles in mitogenic signalling and can be divided into two subfamilies: receptor tyrosine kinases, that have an extracellular ligand binding domain, a single transmembrane domain and an intracellular tyrosine kinase domain and nonreceptor tyrosine kinases, which are soluble, cytoplasmic kinases. (18 Nov 1997) |
| tyrosine N-monooxygenase | <enzyme> Catalyses the n-hydroxylation of l-tyrosine to n-hydroxytyrosine Registry number: EC 1.14.13.41 Synonym: tyrosine n-hydroxylase, haemthiolate enzyme, cytochrome p450(tyr), cyp79 protein (26 Jun 1999) |
| tyrosine phenol-lyase | <enzyme> An enzyme that catalyses the cleavage of tyrosine to phenol, pyruvate, and ammonia. It is a pyridoxal phosphate protein. The enzyme also forms pyruvate from d-tyrosine, l-cysteine, s-methyl-l-cysteine, l-serine, and d-serine, although at a slower rate. Chemical name: L-Tyrosine phenol-lyase (deaminating) Registry number: EC 4.1.99.2 (12 Dec 1998) |
| tyrosine phosphorylation | <enzyme> Kinases that phosphorylate protein tyrosine residues. These kinases play major roles in mitogenic signalling and can be divided into two subfamilies: receptor tyrosine kinases, that have an extracellular ligand binding domain, a single transmembrane domain and an intracellular tyrosine kinase domain and nonreceptor tyrosine kinases, which are soluble, cytoplasmic kinases. (18 Nov 1997) |
| tyrosine-trna ligase | <enzyme> An enzyme that activates tyrosine with its specific transfer RNA. Chemical name: L-Tyrosine:tRNA-(Tyr) ligase (AMP-forming) Registry number: EC 6.1.1.1 (12 Dec 1998) |
| L-tyrosine ammonia-lyase | <enzyme> Catalyses the conversion of tyrosine to trans-p-coumaric acid and ammonia Registry number: EC 4.3.1.- Synonym: tyrosine ammonia-lyase (26 Jun 1999) |
| lymphocyte specific protein tyrosine kinase p56(lck) | <enzyme> This enzyme is a lymphoid specific src family tyrosine kinase that is critical for T-cell development and activation. Lck is associated with the cytoplasmic domains of CD4, CD8 and the beta-chain of the il-2 receptor, and is thought to be involved in the earliest steps of tcr-mediated T-cell activation. Registry number: EC 2.7.11.- (12 Dec 1998) |