A sample of Escherichia coli-expressed human N-RAS-encoded p21, a 21-kDa protein, was selectively labeled with 15N at each of the 14 glycine amide positions. Two-dimensional proton-observe 15N correlation spectra showed one peak for each glycine residue. Five glycine resonances were identified with residues near the nucleotide binding site and provide useful reporters of several oncogene-activa...

A glycine-rich loop in the ATP-binding site is one of the most highly conserved sequence motifs in protein kinases. Each conserved glycine (Gly-50, Gly-52, and Gly-55) in the catalytic (C) subunit of cAMP-dependent protein kinase (cAPK) was replaced with Ser and/or Ala. Active mutant proteins were expressed in Escherichia coli, purified to apparent homogeneity, separated into phosphoisoforms, a...

The maximum velocity of the reaction catalyzed by the pig heart TPN-specific isocitrate dehydrogenase depends on the basic form of an enzymatic group of pK 5.7. This pK is independent of temperature from 10-30” and increases in 20% ethanol, suggesting the ionization of a carboxyl group. The enzyme is inactivated by incubation at pH 7.0 with 1 cyclohexyl3 (2 morpholinoethyl) carbodiimide either ...

To determine the exact potency of inhibitors acting at the glycine site of the NMDA receptor complex using [3H]glycine as a radioligand, the true equilibrium constant (KD) of the radioligand has to be known. To achieve this goal, (1) the contamination of water by glycine was studied, (2) the true affinity of glycine for the NMDA receptor was estimated by different methods, and (3) the inhibitio...

Glycine receptor chloride channels are Cys-loop receptor proteins that isomerize between a low affinity closed state and a high affinity ion-conducting state. There is currently much interest in understanding the mechanisms that link affinity changes with conductance changes. This essentially involves an agonist binding in the glycine receptor ligand-binding site initiating local conformational...

The nucleus accumbens shell (NAc) is a key brain region mediating emotional and motivational learning. In rodent models, dynamic alterations have been observed in synaptic NMDA receptors (NMDARs) within the NAc following incentive stimuli, and some of these alterations are critical for acquiring new emotional/motivational states. NMDARs are prominent molecular devices for controlling neural pla...

The N-methyl-d-aspartate (NMDA) receptor is a ligand-gated ion channel that requires both glutamate and glycine for efficient activation. Here, a strategy combining cysteine scanning mutagenesis and affinity labeling was used to investigate the glycine binding site located on the NR1 subunit. Based on homology modeling to the crystal structure of the glutamate binding site of the 2-amino-3-(3-h...

The NMDA receptor is a key player in excitatory transmission and synaptic plasticity in the central nervous system. Its activation requires the binding of both glutamate and a co-agonist like D-serine to its glycine site. As D-serine is released exclusively by astrocytes, we studied the physiological impact of the glial environment on NMDA receptor-dependent activity and plasticity. To this end...

Some hybrids of vinca alkaloids and phomopsin A, linked by a glycine pattern, have been synthesized in one or two steps, by an insertion reaction and shown to inhibit microtubule assembly. These compounds have been elaborated in order to interact with both the "vinca site" and the "peptide site" of the vinca domain in tubulin. Two out of three hybrids are potent inhibitors of microtubules assem...

A conserved residue at the dihydrofolate binding site of dihydrofolate reductase (EC 1.5.1.3), leucine-54, was replaced with glycine to ascertain the role of this hydrophobic amino acid. The effect of the mutation is both to increase the dissociation rate of dihydrofolate and decrease the rate of hydride transfer thus changing the rate-limiting step in catalysis from product loss (leucine-54) t...