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27-685: 1AZE , 1BM2 , 1BMB , 1CJ1 , 1FHS , 1FYR , 1GCQ , 1GFC , 1GFD , 1GHU , 1GRI , 1IO6 , 1JYQ , 1JYR , 1JYU , 1QG1 , 1TZE , 1X0N , 1ZFP , 2AOA , 2AOB , 2H5K , 2HUW , 2VVK , 2VWF , 2W0Z , 3C7I , 3IMD , 3IMJ , 3IN7 , 3IN8 , 3KFJ , 3MXC , 3MXY , 3N7Y , 3N84 , 3N8M , 3OV1 , 3OVE , 3S8L , 3S8N , 3S8O , 2H46 , 3WA4 , 4P9V , 4P9Z , 5CDW 2885 14784 ENSG00000177885 ENSMUSG00000059923 P62993 Q60631 NM_203506 NM_002086 NM_008163 NM_001313936 NM_001313937 NP_002077 NP_987102 NP_001300865 NP_001300866 NP_032189 Growth factor receptor-bound protein 2 , also known as Grb2 ,

54-564: A growth factor binding to its receptor . Adaptor proteins usually contain several domains within their structure (e.g., Src homology 2 (SH2) and SH3 domains ) that allow specific interactions with several other specific proteins. SH2 domains recognise specific amino acid sequences within proteins containing phosphotyrosine residues and SH3 domains recognise proline -rich sequences within specific peptide sequence contexts of proteins. There are many other types of interaction domains found within adaptor and other signalling proteins that allow

81-447: A polar side group . The word "tyrosine" is from the Greek tyrós , meaning cheese , as it was first discovered in 1846 by German chemist Justus von Liebig in the protein casein from cheese. It is called tyrosyl when referred to as a functional group or side chain. While tyrosine is generally classified as a hydrophobic amino acid, it is more hydrophilic than phenylalanine . It

108-517: A P-X-I/L/V/-D/N-R-X-X-K-P motif that allows it to specifically bind to proteins such as Gab-1. Grb2 has been shown to interact with: Signal transducing adaptor protein Much of the specificity of signal transduction depends on the recruitment of several signalling components such as protein kinases and G-protein GTPases into short-lived active complexes in response to an activating signal such as

135-400: A rich diversity of specific and coordinated protein–protein interactions to occur within the cell during signal transduction . Adaptor proteins include: Tyrosine L -Tyrosine or tyrosine (symbol Tyr or Y ) or 4-hydroxyphenylalanine is one of the 20 standard amino acids that are used by cells to synthesize proteins . It is a conditionally essential amino acid with

162-437: A signalling phosphoprotein may be diverse in their chemical structure. Phosphorylation of the hydroxyl group can change the activity of the target protein, or may form part of a signaling cascade via SH2 domain binding. A tyrosine residue also plays an important role in photosynthesis . In chloroplasts ( photosystem II ), it acts as an electron donor in the reduction of oxidized chlorophyll . In this process, it loses

189-617: A urinary metabolite of tyrosine in rats. Three structural isomers of L-tyrosine are known. In addition to the common amino acid L-tyrosine, which is the para isomer ( para -tyr, p -tyr or 4-hydroxyphenylalanine), there are two additional regioisomers, namely meta -tyrosine (also known as 3-hydroxyphenylalanine , L- m -tyrosine , and m -tyr) and ortho -tyrosine ( o -tyr or 2-hydroxyphenylalanine), that occur in nature. The m -tyr and o -tyr isomers, which are rare, arise through non-enzymatic free-radical hydroxylation of phenylalanine under conditions of oxidative stress . Tyrosine

216-406: Is encoded by the codons UAC and UAU in messenger RNA . The one-letter symbol Y was assigned to tyrosine for being alphabetically nearest of those letters available. Note that T was assigned to the structurally simpler threonine, U was avoided for its similarity with V for valine, W was assigned to tryptophan, while X was reserved for undetermined or atypical amino acids. The mnemonic t Y rosine

243-535: Is a precursor to neurotransmitters and increases plasma neurotransmitter levels (particularly dopamine and norepinephrine), but has little if any effect on mood in normal subjects. A 2015 systematic review found that "tyrosine loading acutely counteracts decrements in working memory and information processing that are induced by demanding situational conditions such as extreme weather or cognitive load " and therefore "tyrosine may benefit healthy individuals exposed to demanding situational conditions". L-tyrosine

270-527: Is also presented in serine and threonine , whose side chains have a hydroxy group, but are alcohols . Phosphorylation of these three amino acids' moieties (including tyrosine) creates a negative charge on their ends, that is greater than the negative charge of the only negatively charged aspartic and glutamic acids. Phosphorylated proteins keep these same properties—which are useful for more reliable protein-protein interactions—by means of phosphotyrosine, phosphoserine and phosphothreonine. Binding sites for

297-445: Is also the precursor to the pigment melanin . Tyrosine (or its precursor phenylalanine) is needed to synthesize the benzoquinone structure which forms part of coenzyme Q10 . The decomposition of L-tyrosine (syn. para -hydroxyphenylalanine) begins with an α-ketoglutarate dependent transamination through the tyrosine transaminase to para -hydroxyphenylpyruvate . The positional description para , abbreviated p , mean that

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324-551: Is an adaptor protein involved in signal transduction / cell communication . In humans, the GRB2 protein is encoded by the GRB2 gene . The protein encoded by this gene binds receptors such as the epidermal growth factor receptor and contains one SH2 domain and two SH3 domains . Its two SH3 domains direct complex formation with proline -rich regions of other proteins, and its SH2 domain binds tyrosine phosphorylated sequences. This gene

351-422: Is called phosphotyrosine . Tyrosine phosphorylation is considered to be one of the key steps in signal transduction and regulation of enzymatic activity. Phosphotyrosine can be detected through specific antibodies . Tyrosine residues may also be modified by the addition of a sulfate group, a process known as tyrosine sulfation . Tyrosine sulfation is catalyzed by tyrosylprotein sulfotransferase (TPST). Like

378-416: Is catalyzed by the enzyme phenylalanine hydroxylase , a monooxygenase. This enzyme catalyzes the reaction causing the addition of a hydroxyl group to the end of the 6-carbon aromatic ring of phenylalanine , such that it becomes tyrosine. Some of the tyrosine residues can be tagged (at the hydroxyl group) with a phosphate group ( phosphorylated ) by protein kinases . In its phosphorylated form, tyrosine

405-440: Is produced via prephenate , an intermediate on the shikimate pathway . Prephenate is oxidatively decarboxylated with retention of the hydroxyl group to give p -hydroxyphenylpyruvate, which is transaminated using glutamate as the nitrogen source to give tyrosine and α-ketoglutarate . Mammals synthesize tyrosine from the essential amino acid phenylalanine (Phe), which is derived from food. The conversion of Phe to Tyr

432-454: Is similar to the sem-5 gene of Caenorhabditis elegans , which is involved in the signal transduction pathway. Two alternatively spliced transcript variants encoding different isoforms have been found for this gene. Grb2 is widely expressed and is essential for multiple cellular functions. Inhibition of Grb2 function impairs developmental processes in various organisms and blocks transformation and proliferation of various cell types. It

459-527: Is thus not surprising that targeted gene disruption of Grb2 in mice is lethal at an early embryonic stage. Grb2 is best known for its ability to link the epidermal growth factor receptor tyrosine kinase to the activation of Ras and its downstream kinases, ERK1,2 . Grb2 is composed of an SH2 domain flanked on each side by an SH3 domain . Grb2 has two closely related proteins with similar domain organizations, Gads and Grap . Gads and Grap are expressed specifically in hematopoietic cells and function in

486-406: Is used in pharmaceuticals , dietary supplements , and food additives . Two methods were formerly used to manufacture L-tyrosine. The first involves the extraction of the desired amino acid from protein hydrolysates using a chemical approach. The second utilizes enzymatic synthesis from phenolics, pyruvate, and ammonia through the use of tyrosine phenol-lyase . Advances in genetic engineering and

513-494: The colloid of the thyroid are also derived from tyrosine. The latex of Papaver somniferum , the opium poppy, has been shown to convert tyrosine into the alkaloid morphine and the bio-synthetic pathway has been established from tyrosine to morphine by using Carbon-14 radio-labelled tyrosine to trace the in-vivo synthetic route. Tyrosine ammonia lyase (TAL) is an enzyme in the natural phenols biosynthesis pathway. It transforms L-tyrosine into p-coumaric acid . Tyrosine

540-400: The addition of a water molecule. Thereby fumarate (also a metabolite of the citric acid cycle) and acetoacetate (3-ketobutyroate) are liberated. Acetoacetate is a ketone body , which is activated with succinyl-CoA, and thereafter it can be converted into acetyl-CoA , which in turn can be oxidized by the citric acid cycle or be used for fatty acid synthesis . Phloretic acid is also

567-469: The body from phenylalanine, is found in many high- protein food products such as meat , fish , cheese , cottage cheese , milk , yogurt , peanuts , almonds , pumpkin seeds , sesame seeds , soy protein and lima beans . For example, the white of an egg has about 250 mg per egg, while beef, lamb, pork, tuna, salmon, chicken, and turkey contain about 500–1000 mg per 3 ounces (85 g) portion. In plants and most microorganisms, tyrosine

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594-524: The coordination of tyrosine kinase mediated signal transduction . The SH2 domain of Grb2 binds to phosphorylated tyrosine-containing peptides on receptors or scaffold proteins with a preference for pY-X-N-X, where X is generally a hydrophobic residue such as valine (see [1] ). The N-terminal SH3 domain binds to proline-rich peptides and can bind to the Ras-guanine exchange factor SOS . The C-terminal SH3 domain binds to peptides conforming to

621-471: The hydrogen atom of its phenolic OH-group. This radical is subsequently reduced in the photosystem II by the four core manganese clusters . The Dietary Reference Intake for tyrosine is usually estimated together with phenylalanine . It varies depending on an estimate method, however the ideal proportion of these two amino acids is considered to be 60:40 (phenylalanine:tyrosine) as a human body has such composition. Tyrosine, which can also be synthesized in

648-405: The hydroxyl group and side chain on the phenyl ring are across from each other (see the illustration below). The next oxidation step catalyzes by p -hydroxyphenylpyruvate dioxygenase and splitting off CO 2 homogentisate (2,5-dihydroxyphenyl-1-acetate). In order to split the aromatic ring of homogentisate, a further dioxygenase, homogentisate 1,2-dioxygenase is required. Thereby, through

675-409: The incorporation of a further O 2 molecule, maleylacetoacetate is created. Fumarylacetoacetate is created by maleylacetoacetate cis - trans -isomerase through rotation of the carboxyl group created from the hydroxyl group via oxidation. This cis-trans -isomerase contains glutathione as a coenzyme . Fumarylacetoacetate is finally split by the enzyme fumarylacetoacetate hydrolase through

702-559: The phosphotyrosine antibodies mentioned above, antibodies have recently been described that specifically detect sulfotyrosine. In dopaminergic cells in the brain , tyrosine is converted to L-DOPA by the enzyme tyrosine hydroxylase (TH). TH is the rate-limiting enzyme involved in the synthesis of the neurotransmitter dopamine . Dopamine can then be converted into other catecholamines , such as norepinephrine (noradrenaline) and epinephrine (adrenaline). The thyroid hormones triiodothyronine (T 3 ) and thyroxine (T 4 ) in

729-477: Was also proposed. Aside from being a proteinogenic amino acid , tyrosine has a special role by virtue of the phenol functionality. Its hydroxy group is able to form the ester linkage , with phosphate in particular. Phosphate groups are transferred to tyrosine residues by way of protein kinases . This is one of the post-translational modifications . Phosphorylated tyrosine occurs in proteins that are part of signal transduction processes. Similar functionality

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