1. Experiments were performed to throw light on why the incorporation of (14)C from labelled carbohydrate precursors into glutamate has been found to be more marked in brain than in other tissues. 2. Rapid isotope exchange between labelled glutamate and unlabelled alpha-oxoglutarate was demonstrated in brain and liver mitochondrial preparations. In the presence but not in the absence of alpha-o...

The α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors (AMPARs) are major excitatory receptors that mediate fast neurotransmission in the mammalian brain. The surface expression of functional AMPARs is crucial for synaptic transmission and plasticity. AMPAR auxiliary subunits control the biosynthesis, membrane trafficking, and synaptic targeting of AMPARs. Our ...

A characteristic consequence of a biotin deficiency in animals is a decreased ability to fix C402 into various tissue components including the amino acid arginine (1). Carbon dioxide is incorporated into arginine as a result of the conversion of ornithine to citrulline in the Krebs-Henseleit urea cycle (2). The methods developed by Cohen and Hayano (3, 4) for the synthesis of citrulline from or...

The efflux of methotrexate and methotrexate polyglutamates was examined with primary monolayer cultures of rat hepatocytes and also with monolayer cultures of a stable hepatocarcinoma cell line (H35 cells). In this study, the polyglutamates were considered as those species with two or more additional glutamate residues. When methotrexate polyglutamates were present in hepatocytes in excess of m...

Hydrogen ions are important regulators of ion flux through voltage-gated Ca 2+ channels but their site of action has been controversial. To idendfy molecular determinants of proton block of L-type Ca 2+ channels, we combined site-directed mutagenesis and unitary current recordings from wild-type (WT) and mutant L-type Ca 2§ channels expressed in Xen0pus oocytes. WT channels in 150 mM K + displa...

The unique taste of umami argues for a specific receptor at the taste cell level. The taste synergism between monosodium glutamate (MSG) and certain 59-ribonucleotides provides a pharmacologic test for hypothetical mechanisms of umami taste. Early neurophysiologic and biochemical studies demonstrated specific recognition of L-glutamate by taste tissue and suggested that the synergism found with...

We have designed and synthesized four-R-helix-bundle proteins that accommodate heme groups to act as molecular “maquettes” of more complex natural electron-transfer proteins. These bundles can be oriented at an air-water interface and transferred onto solid surfaces to facilitate the exploration of the factors that govern biological electron transfer. We find that the orientation of these maque...

C-type natriuretic peptide (CNP) activation of the guanylyl cyclase-linked natriuretic peptide receptor-B (NPR-B) stimulates vasorelaxation and bone growth. Hormones and phorbol esters (PMA) inhibit NPR-B in calcium and protein kinase c-dependent manners, respectively. Here, we characterize the kinetic properties of NPR-B in membranes from cells exposed to PMA, the calcium ionophore, ionomycin,...