Structural changes in glycogen phosphorylase induced by phosphorylation.

S R Sprang; K R Acharya; E J Goldsmith; D I Stuart; K Varvill; R J Fletterick; N B Madsen; L N Johnson

doi:10.1038/336215a0

Home/Archive/PubMed

PubMed · 3194008

Structural changes in glycogen phosphorylase induced by phosphorylation.

S R Sprang·K R Acharya·E J Goldsmith·D I Stuart·K Varvill·R J Fletterick·N B Madsen·L N Johnson

View original source ↗Export metadata ↓

Abstract

A comparison of the refined crystal structures of dimeric glycogen phosphorylase b and a reveals structural changes that represent the first step in the activation of the enzyme. On phosphorylation of serine-14, the N-terminus of each subunit assumes an ordered helical conformation and binds to the surface of the dimer. The consequent structural changes at the N- and C-terminal regions lead to strengthened interactions between subunits and alter the binding sites for allosteric effectors and substrates.

Explore related subjects

Adenosine Monophosphate Allosteric Site Chemical Phenomena Chemistry, Physical Enzyme Activation Glucose-6-Phosphate Glucosephosphates Hydrogen Bonding Macromolecular Substances Phosphorylases Phosphorylation Phosphoserine Protein Conformation X-Ray Diffraction Comparative Study Journal Article Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S.

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

S R Sprang, K R Acharya, E J Goldsmith, D I Stuart, K Varvill, R J Fletterick, N B Madsen, L N Johnson. 1988-11-17. Structural changes in glycogen phosphorylase induced by phosphorylation.. https://doi.org/10.1038/336215a0

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Phospho-dependent functional modulation of GABA(B) receptors by the metabolic sensor AMP-dependent protein kinase.

GABA(B) receptors are heterodimeric G protein-coupled receptors composed of R1 and R2 subunits that mediate slow synaptic inhibition in the brain by activating inwardly rectifying K(+) channels (GIRKs) and inhibiting Ca(2+) channels. We demonstrate here that GABA(B) receptors are intimately associated with 5'AMP-dependent protein kinase (AMPK). AMPK acts as a metabolic sensor that is potently activated by increases in 5'AMP concentration that are caused by enhanced metabolic activity, anoxia, or ischemia. AMPK binds the R1 subunit and directly phosphorylates S783 in the R2 subunit to enhance GABA(B) receptor activation of GIRKs. Phosphorylation of S783 is evident in many brain regions, and is increased dramatically after ischemic injury. Finally, we also reveal that S783 plays a critical role in enhancing neuronal survival after ischemia. Together our results provide evidence of a neuroprotective mechanism, which, under conditions of metabolic stress or after ischemia, increases GABA(B) receptor function to reduce excitotoxicity and thereby promotes neuronal survival.

Adenosine Monophosphate↗

PubMed2007

Bronchial responsiveness to methacholine and adenosine 5'-monophosphate in atopic and non-atopic preschool children with recurrent wheezing.

BACKGROUND: It is well known that atopy is a major determinant of bronchial hyper-responsiveness (BHR) in both asymptomatic and asthmatic children. However, the relationship between atopy and BHR has not been well studied in preschool children with wheezing. BHR is usually measured by bronchial challenges using direct and indirect stimuli. OBJECTIVE: The aim of this study was to investigate whether atopic and non-atopic preschool wheezers display similar or different BHR profiles for direct and indirect stimuli. METHODS: Methacholine and adenosine 5'-monophosphate (AMP) bronchial challenges were performed in 4 to 6-year-old children with recurrent wheezing, using a modified auscultation method. The end-point was defined as the appearance of wheezing and/or oxygen desaturation. Atopy was determined to be present when a child had at least one positive reaction to a panel of 13 common airborne allergens in the presence of positive and negative controls. RESULTS: A positive response to methacholine (an end-point concentration < or =8 mg/mL) was observed in 89.3% (50/56) of atopic wheezers and in 83.8% (31/37) of non-atopic wheezers (P=0.44) for the difference. By contrast, the frequency of a positive response to AMP (an end-point concentration < or =200 mg/mL) was significantly higher in the atopic group (47/56, 83.9%) compared with the non-atopic group (12/37, 32.4%; P<0.01). CONCLUSION: While a majority of both atopic and non-atopic preschool wheezers were hyper-responsive to methacholine, atopic subjects were more hyper-responsive to AMP than non-atopic subjects. These findings suggest that atopic and non-atopic wheeze in preschool children are related to distinctive pathophysiologic pathways.

Adenosine Monophosphate↗

PubMed2006

Lysyl-tRNA synthetase-generated lysyl-adenylate is a substrate for histidine triad nucleotide binding proteins.

Histidine triad nucleotide binding proteins (Hints) are the most ancient members of the histidine triad protein superfamily of nucleotidyltransferases and hydrolyases. Protein-protein interaction studies have found that complexes of the transcription factors MITF or USF2 and lysyl-tRNA synthetase (LysRS) are associated with human Hint1. Therefore, we hypothesized that lysyl-AMP or the LysRS.lysyl-AMP may be a native substrate for Hints. To explore the biochemical relationship between Hint1 and LysRS, a series of catalytic radiolabeling, mutagenesis, and kinetic experiments was conducted with purified LysRSs and Hints from human and Escherichia coli. After incubation of the E. coli or human LysRS with Hints and [alpha-(32)P]ATP, but not [alpha-(32)P]GTP, (32)P-labeled Hints were observed. By varying time and the concentrations of lysine, Mg(2+), or LysRS, the adenylation of Hint was found to be dependent on the formation of lysyl-AMP. Site-directed mutagenesis studies of the active site histidine triad revealed that Hint labeling could be abolished by substitution of either His-101 of E. coli hinT or His-112 of human Hint1 by either alanine or glycine. Ap(4)A, believed to be synthesized by LysRS in vivo, and Zn(2+) were shown to inhibit the formation of Hint-AMP with an IC(50) value in the low micromolar range. Consistent with pyrophosphate being an inhibitor for aminoacyl-tRNA synthetase, incubations in the presence of pyrophosphatase resulted in enhanced formation of Hint-AMP. These results demonstrate that the lysyl-AMP intermediate formed by LysRS is a natural substrate for Hints and suggests a potential highly conserved regulatory role for Hints on LysRS and possibly other aminoacyl-tRNA synthetases.

Adenosine Monophosphate↗