Structural Characterization of an LPA1 Second Extracellular Loop Mimetic with a Self-Assembling Coiled-Coil Folding Constraint.

G protein-coupled receptor (GPCR) structures are of interest as a means to understand biological signal transduction and as tools for therapeutic discovery. The growing number of GPCR crystal structures demonstrates that the extracellular loops (EL) connecting the membrane-spanning helices show tremendous structural variability relative to the more structurally-conserved seven transmembrane α-helical domains. The EL of the LPA(1) receptor have not yet been conclusively resolved, and bear limited sequence identity to known structures.

Proteins related to the Nedd4 family of ubiquitin protein ligases interact with the L domain of Rous sarcoma virus and are required for gag budding from cells.

The late assembly (L) domain of retrovirus Gag, required in the final steps of budding for efficient exit from the host cell, is thought to mediate its function through interaction with unknown cellular factors. Here, we report the identification of the Nedd4-like family of E3 ubiquitin protein ligases as proteins that specifically interact with the Rous sarcoma virus (RSV) L domain in vitro and in vivo. We screened a chicken embryo cDNA expression library by using a peptide derived from the RSV p2b sequence, isolating two unique partial cDNA clones.

Tsg101, a homologue of ubiquitin-conjugating (E2) enzymes, binds the L domain in HIV type 1 Pr55(Gag).

Ubiquitination appears to be involved in virus particle release from infected cells. Free ubiquitin (Ub), as well as Ub covalently bound to a small fraction of p6 Gag, is detected in mature HIV particles. Here we report that the p6 region in the Pr55(Gag) structural precursor polyprotein binds to Tsg101, a putative Ub regulator that is involved in trafficking of plasma membrane-associated proteins.

Mechanism of inhibition of aldehyde dehydrogenase by citral, a retinoid antagonist.

Low concentrations of citral (3,7-dimethyl-2,6-octadienal), an inhibitor of retinoic acid biosynthesis, inhibited E1, E2 and E3 isozymes of human aldehyde dehydrogenase (EC1.2.1.

Methylglyoxal as substrate and inhibitor of human aldehyde dehydrogenase: comparison of kinetic properties among the three isozymes.

Methylglyoxal was demonstrated to be a substrate for the isozymes E1, E2 and E3 of human aldehyde dehydrogenase. Pyruvate was the product from the oxidation of methylglyoxal by the three isozymes. At pH 7.

Drug-resistant HIV-1 proteases identify enzyme residues important for substrate selection and catalytic rate.

A series of mutations, first identified in protease inhibitor-resistant HIV-1 viral isolates, were introduced into HIV-1 PR as individual substitutions. Mutants containing R8K, V32I, V82T, I84V, G48V/L90M, or V82T/I84V substitutions were analyzed for differences in substrate preference and catalytic efficiency using a set of single amino acid substituted HIV-1 CA-NCa cleavage site peptides. All mutants exhibited wild-type preference for large hydrophobic residues, especially Phe, in the P1' substrate position.

Tissue distribution of human aldehyde dehydrogenase E3 (ALDH9): comparison of enzyme activity with E3 protein and mRNA distribution.

The tissue distribution of the E3 isozyme of human aldehyde dehydrogenase has been investigated by three methods: enzyme activity assay employing betaine aldehyde as substrate, Western blotting employing E3 isozyme-specific antibodies, and Northern blotting using a human liver E3 cDNA as probe. All three methods showed that E3 isozyme was universally distributed among all tissues tested. The highest levels of the E3 isozyme activity were found in liver, adrenal gland, and kidney.

Cimetidine and other H2-receptor antagonists as inhibitors of human E3 aldehyde dehydrogenase.

The histamine H2-receptor antagonists have been identified as inhibitors of human liver aldehyde dehydrogenase (EC 1.2.1.

Aldehyde dehydrogenase from adult human brain that dehydrogenates gamma-aminobutyraldehyde: purification, characterization, cloning and distribution.

Enzyme purification and characterization, cDNA cloning and Northern blot analysis were the techniques utilized during this investigation to determine the identity and occurrence of the aldehyde dehydrogenase that metabolizes gamma-aminobutyraldehyde in adult human brain. The purification yielded one major protein which was active with gamma-aminobutyraldehyde. It had the physico-chemical and kinetic properties of the human liver E3 isoenzyme of aldehyde dehydrogenase (EC 1.