Phosphate group, attachment

PTEN is a phosphatase, which is a product of a tumor suppressor gene. This phosphatase has an unusual broad specificity and can remove phosphate groups attached to serine, threonine, and tyrosine residues. It is believed that its ability to dephosphorylate phosphati-dylinositol (PI) 3,4,5-triphosphate, the product of PI-3 kinase, is responsible for its tumor suppressor effects. 

Starch molecules have many exposed O—bonds, so this phosphorylation reaction results in multiple phosphate groups attached to each starch molecule. The remaining —OH group on each phosphate can condense with an O— H bond on another starch molecule. This cross-linking of starch chains gives the desired thick consistency of puddings and pies. 

Nucleoside reverse transcriptase inhibitor (NRTI)/nucleotide reverse transcriptase inhibitor (NtRI) A modified version of a naturally-occurring nucleoside or nucleotide that prevents human immunodeficiency virus (HIV) replication by interfering with the function of the viral reverse transcriptase enzyme. The nucleoside/nucleotide analog causes early termination of the proviral DNA chain. For activity, an NRTI requires three phosphorylation steps once inside the cell, whereas an NtRI has a phosphate group attached and needs only two phosphorylation steps inside the cell for activity. 

Cyanine dyes containing one or two phosphate groups attached directly to the aromatic indolenine residues were recently reported by M. Reddington [26],... 

The deoxyribonucleotides in the DNA polymer are connected by phosphodi-ester bonds between the 5 -phosphate group attached to one deoxyribose sugar and the 3 -hydroxyl group of the next sugar. 

Before a nucleoside, such as guanosine, can be incorporated into RNA or DNA, it must be activated by having three phosphate groups attached to it. 

This is a reaction between an M f alcohol (R-OH) and an acid (HPO42-) to produce an ester (a phosphate ester). Note that glucose 6-phosphate has a phosphate group attached to Cg, where Ci is the aldehyde carbon. 

Figure 16.1 The structure of adenosine triphosphate (ATP). The lower ring is a ribose sugar, the upper molecule is the base, adenine. Adenosine diphosphate (ADP) differs from ATP by having two phosphate groups attached instead of three.

Figure 6.2. Molecular architecture of DNA. Each strand of DNA is composed of alternating pentose sugar (deoxyribose) and phosphate moieties linked to each other via phosphodiester linkage. The first carbon position of the sugar is attached to one of the four nitrogenous bases (A, T, G, or C). The two strands are in opposite orientation to each other with respect to a 5 or 3 phosphate group attached to the sugar moiety. Cytosine (C) pairs with guanine (G) via three hydrogen bonds, and adenine (A) pairs with thymine (T). (Reproduced from Textbook of Biochemistry with Clinical Correlations, T. M. Devlin, ed., Wiley, New York, 1982.)...

Nucleotides differ from nucleosides in that they have phosphate groups attached to either the 3 or 5 position of the sugar. The structures of deoxyadenosine 5 -monophosphate,... 

Nucleotide (Section 27.1) A nucleoside that has a phosphate group attached to the sugar. 

By convention, numbering of the bases is unprimed and numbering of the sugars is primed. A nucleic acid polymer typically has the phosphate group attached to the 5 position of the first nucleotide (the 5 end), and the other end terminates in a hydroxyl group at the 3 position of the sugar of the last nucleotide (the 3 end). By convention, nucleotide sequences are almost always read and presented in the 5 to 3 direction. The sequence maybe presented in unbroken form or in evenly spaced blocks. 

ADP (adenosine diphosphate) contains a second phosphate group attached to the phosphate of AMP by an anhydride bond. 

Phospholipid I A lipid made up of glycerol and fatty acids, with a phosphate group attached. 

DNA and RNA each consist of only four different nucleotides. Recall from Chapter 2 that all nucleotides consist of an organic base linked to a five-carbon sugar that has a phosphate group attached to carbon 5. In RNA, the sugar is rlbose in DNA, deoxyribose (see Figure 2-14). The nucleotides used in synthesis of DNA and RNA contain five different bases. The bases adenine (A) and guanine (G) are purines, which con-... 

---